Mileage Audit Defense for Self-Employed Drivers

A mileage audit is a paperwork problem disguised as a tax problem. The IRS does not need to prove you were never on the road. Under IRC §274(d), you have to prove you were — with the right records, kept the right way, before anyone asked.

That single sentence explains why the Tax Court has thrown out billion-dollar-equivalent mileage deductions from people who actually drove the miles. It also explains why a $9 iOS app sitting in your pocket can be the difference between a 0% adjustment and a $7,000 bill plus a 20% penalty.

This playbook covers both audiences who tend to land here: the pre-audit reader building a defensible record before anything happens, and the mid-audit reader who just opened a CP2000 or Letter 525 and needs to know what to do in the next 30 days. Tax professionals advising self-employed clients will find the statutory framework laid out plainly, with verified Tax Court citations throughout.

Key takeaways

• §274(d) treats your car as “listed property” and demands strict substantiation — the Cohan rule that lets you estimate other deductions does not apply here.
• The 20% accuracy-related penalty under §6662 kicks in fast — it’s the greater of $5,000 or 10% of the corrected tax. First-Time Abatement does not apply to it.
• Reconstructed logs lose. Velez, Garza, Royster, Khan, DeLima, and Craddock all rejected after-the-fact reconstructions.
• Contemporaneous electronic logs win. Patitz v. Commissioner, T.C. Memo. 2022-99, allowed deductions because the taxpayer’s electronic mileage log was contemporaneous and credible.
• The 90-day Notice of Deficiency is statutory under §6213(a). You cannot extend it. Miss it and you lose your only pre-payment forum.
• Automating contemporaneous capture — GPS-stamped routes, per-trip business purpose, timestamps — is the cheapest insurance you can buy.

Two readers, one playbook

If you are reading this in advance of any IRS contact, your job is simple but unforgiving: build a contemporaneous record now so that an examiner sees nothing worth disputing. The whole article applies to you, but pay special attention to the sections on §274(d), the home-office unlock, and the document checklist.

If you are reading this because you just opened an envelope with a notice in it, take a breath. The most common mileage audit is a correspondence audit — handled entirely by mail, scope limited to one or two line items. You have time. You have rights. And you have leverage if you build the response properly. The IDR walkthrough, the 30/30/90 timeline section, and the §6664(c) reasonable-cause section are written for you.

Both readers should know one number up front. Of the 505,514 audits the IRS closed in fiscal year 2024, 77.9% were correspondence audits, and they generated about $6 billion in adjustments. Field audits made up the remaining 22.1% but generated $23 billion — roughly four times the revenue per audit. A mileage-focused exam on a Schedule C return almost always lands in the correspondence bucket unless other large issues are open.

Why mileage is the most-audited Schedule C line

Three features make Line 9 (Car and Truck Expenses) an examiner’s favorite target.

First, the math is large. At the 2026 standard mileage rate of 72.5¢/mile (Notice 2026-10), a self-employed driver claiming 18,000 business miles is deducting $13,050. That’s a real number against ordinary income tax and 15.3% self-employment tax. (For a full walk-through of the 2026 rate and the OBBBA changes that surround it, see our IRS Mileage Rate 2026 guide.)

Second, the substantiation rule is strict and well-litigated. Treas. Reg. §1.274-5(b)(6) requires four elements per trip: amount (miles), time (date), place (destination), and business purpose. Treas. Reg. §1.274-5T(c)(2)(ii)(A) says the record must be “made at or near the time” of the expense — though a “log maintained on a weekly basis” is explicitly considered contemporaneous. That sentence is the safe harbor most drivers fail.

Third, mileage is one of the few line items where a thorough auditor can disallow the entire deduction with a single doctrinal move. Other deductions can be estimated under the Cohan rule. Mileage cannot.

How the IRS picks you — DIF, UIDIF, and the obvious triggers

Every individual return gets a Discriminant Function (DIF) score and a UIDIF (Unreported Income DIF) score the moment it’s processed. The formulas are not public, but the IRS has confirmed they compare your return to statistical norms for similar taxpayers — same income, same industry, same geography. Higher scores feed a manual screening queue, and a subset of those become exams.

Several patterns reliably raise the score for self-employed Schedule C filers:

• High expense-to-receipts ratio. Reporting $135,000 in expenses against $150,000 in receipts when industry norms cluster near 60% is a flag.
• Repeated losses. Under IRC §183, an activity that fails to show profit in 3 of 5 years (2 of 7 for horse activities) invites reclassification as a hobby — disallowing every deduction.
• Round-number expenses. “$5,000 in mileage” is suspicious because real mileage is messy.
• Home office plus very high mileage. Each is fine alone. Together they invite a question: if you work from home, are those trips really business?
• Cash-intensive businesses. Salons, restaurants, rideshare, construction subs — anywhere bank-deposit analysis is the IRS’s first move.
• 1099-NEC mismatches. This is the most automatic trigger. If a client reports paying you $42,000 on a 1099-NEC and your Schedule C shows $38,000, the IRS Automated Underreporter program generates a CP2000 notice without a human ever touching the file. AUR alone produced $7.7 billion in additional assessments in FY 2024. (Our freelancer and 1099 contractor guide walks through 1099 reconciliation in detail.)

One OBBBA change matters here. P.L. 119-21 §70433 raises the 1099-NEC reporting threshold from $600 to $2,000 for payments made after December 31, 2025. Fewer small payments will trigger automatic 1099 mismatches starting with the 2026 tax year — but the rule for 2025 income (filed in early 2026) is still $600.

The three audit flavors

Correspondence audit (77.9% of audits). Mail-based, scope-limited. Usually starts with CP2000, Letter 566, Letter 2202, or for Schedule C examination findings, Letter 525 with the Revenue Agent’s Report on Form 4549. This is what most mileage disputes look like.

Office audit. You (or your representative) bring records to a local IRS office. Broader scope, typical for itemized Schedule A audits and mid-complexity Schedule C cases. Started by Letter 3572 or 3573.

Field audit. A revenue agent visits your home or business. Reserved for higher-income, multi-entity, or complex returns. Often examines multiple years. Duration: 6–18 months, sometimes longer. This is where bank-deposit analyses, employee interviews, and premises tours happen.

For a self-employed driver with a single-issue mileage challenge, expect correspondence. Plan as if it might become office.

§274(d) — the rule that wrecks unprepared drivers

IRC §274(d) is the audit clause you need to memorize. It says no deduction is allowed for any traveling expense, gift, or use of listed property unless you substantiate by adequate records or sufficient corroborating evidence: (a) the amount, (b) the time and place, (c) the business purpose, and (d) where applicable, the business relationship.

IRC §280F(d)(4) defines listed property to include passenger automobiles. Translation: your car is listed property, and the strict rule applies to every business mile you claim.

Treas. Reg. §1.274-5(b)(6) breaks the requirement into four discrete elements for each business use of a vehicle: amount (miles per trip plus total annual miles), date, place, and business purpose. Skip any one and the trip fails substantiation.

Treas. Reg. §1.274-5T(c)(2)(ii)(A) is the section that turns “contemporaneous” into a defensible standard. The record must be “made at or near the time” of the use — but the regulation explicitly says “a log maintained on a weekly basis, which accounts for use during the week, shall be considered a record made at or near the time of such use.” A weekly cadence is the floor; trip-by-trip GPS capture sits comfortably above it.

The rule has a corollary that catches many drivers off guard. Rev. Rul. 99-7 treats commuting between your residence and a regular work location as nondeductible personal travel — unless your home qualifies as your principal place of business under §280A(c)(1)(A). If your home office passes the “exclusive and regular use” test and is your principal place of business, every trip from home to a client or job site becomes business mileage. That single legal switch can convert thousands of nondeductible commuting miles per year into deductible ones. It’s also the reason auditors who see a home office automatically check whether it actually qualifies.

Why Cohan won’t save you

In Cohan v. Commissioner, 39 F.2d 540 (2d Cir. 1930), Judge Learned Hand told the IRS it had to estimate Broadway producer George M. Cohan’s travel and entertainment expenses, “bearing heavily if it chooses upon the taxpayer whose inexactitude is of his own making.” That phrase echoed through tax law for decades.

Congress closed the door for vehicle expenses. The Tax Court in Sanford v. Commissioner, 50 T.C. 823 (1968), aff’d 412 F.2d 201 (2d Cir. 1969), held that §274(d) overrides Cohan for the items it covers — travel, listed property, and (pre-TCJA) entertainment. Every subsequent mileage case confirms the result.

The plain-English version: for most business expenses, you can estimate. For your car, you cannot. If §274(d) substantiation is missing, the deduction goes to zero — even when the court agrees you actually drove for business.

The §6662 accuracy-related penalty — with full dollar math

A disallowed mileage deduction is just the beginning. Under IRC §6662(a), the IRS adds a 20% accuracy-related penalty to any portion of an underpayment attributable to:

• Negligence or disregard of rules (§6662(b)(1)) — defined as a failure to make a reasonable attempt to comply, including failure to keep adequate books and records.
• Substantial understatement of income tax (§6662(b)(2)) — meaning an understatement exceeding the greater of $5,000 or 10% of the tax required to be shown (§6662(d)).

For a self-employed driver, both prongs typically trigger when a mileage deduction is fully disallowed.

The math, end to end. Assume you claimed 22,000 business miles in 2026 at 72.5¢/mile — a $15,950 Schedule C deduction. The IRS disallows the entire amount.

For a deduction that would have been perfectly legal had you logged it properly.

The penalty exists in the statute partly to make this exact calculation feel inevitable. First-Time Abatement does not apply to §6662 (IRM 20.1.1.3.3.2.1 limits FTA to failure-to-file, failure-to-pay, and failure-to-deposit penalties). Your only meaningful escape is the reasonable-cause defense.

Reasonable cause under §6664(c) — what works, what doesn’t

IRC §6664(c) provides that no §6662 penalty applies to any portion of an underpayment if the taxpayer shows reasonable cause and acted in good faith. Treas. Reg. §1.6664-4(b) makes the test fact-specific and notes that “the most important factor is the extent of the taxpayer’s effort to assess the taxpayer’s proper tax liability.”

In practice, three patterns succeed and three fail.

Tends to succeed:

• Reliance on a tax professional who was given complete and accurate information, where the professional’s advice was the source of the position.
• Good-faith use of a credible mileage-tracking system that captured trips contemporaneously, even if some entries had errors.
• An honest mistake on a complex area of law, documented at the time.

Tends to fail:

• “I lost my records.” (Rejected in DeLima — and the burden is on you to maintain them.)
• “I thought my calendar was enough.” (Rejected in Garza.)
• “I reconstructed it from memory.” (Rejected in Velez and Khan.)

A clean reasonable-cause letter cites §6664(c), describes the substantiation system you actually used, includes the records you have, and explains any gap in plain terms. EveryLastMile users who can show a continuous GPS-stamped log start the conversation from a far stronger position than drivers reconstructing from memory.

Who bears the burden — §7491(a) explained

The default rule: the taxpayer has the burden of proof in Tax Court. IRC §7491(a) shifts that burden to the IRS on a factual issue only if all of the following are true:

1. You introduce credible evidence with respect to the factual issue;
2. You complied with the Code’s substantiation requirements for the item;
3. You maintained all required records; and
4. You cooperated with reasonable IRS requests for witnesses, information, documents, meetings, and interviews.

For mileage cases, this is largely theoretical. If you fail §274(d) substantiation, you fail condition (2), and the burden never shifts. If you meet §274(d), you usually don’t need the burden shift because your records carry the deduction on their own. Burden shifting matters most in disputes where the dollar issue is not §274(d) — for example, whether a particular trip was personal or business given that all four substantiation elements are documented.

Form 4564 — the Information Document Request, decoded

If your audit moves past the initial notice, the IRS will send a Form 4564 — Information Document Request (IDR). It identifies the records sought, the period in scope, and a response date — normally 30 days.

A mileage-focused IDR typically asks for:

1. The contemporaneous mileage log for the year (date, destination, business purpose, miles).
2. Beginning and ending odometer readings for every vehicle used in business.
3. Vehicle service or maintenance records that show odometer readings.
4. Title and registration for each vehicle.
5. Auto insurance declarations showing business/personal use designation.
6. Your calendar or appointment book for the year.
7. Client invoices, emails, contracts, or dispatch records showing the locations served.
8. Bank and credit-card statements covering fuel, parking, and tolls.
9. Receipts for any actual-expense items, if you used the actual method.
10. Depreciation schedule and prior-year returns (if claiming depreciation).
11. Lease agreement (if leased).
12. A list of all vehicles owned or leased during the year and the percentage used for business.

The first three items together let an examiner reconstruct two things: your total annual miles (from odometer readings and service records) and your business miles (from your log). Their ratio is your business-use percentage. Documenting both halves separately is far more persuasive than presenting one number. (If you’re choosing between standard mileage and actual expenses, our standard mileage vs. actual expenses guide explains why actual-method audits typically require 3× the documentation.)

How to respond to a Form 4564 IDR

1. Verify the notice is legitimate. Confirm the agent’s name and badge number on the IRS phone directory before sending anything. Phishing audit-bait letters exist.
2. Identify scope. Read the IDR carefully. It will list specific years and specific items. Do not volunteer materials outside scope.
3. Calendar the deadline. Default is 30 days from the date of the IDR. If you need more time, call the agent before the deadline — first extensions of 14–30 days are routinely granted for reasonable cause.
4. Pull the contemporaneous records. Export your mileage log, calendar, and supporting communications. If you use EveryLastMile, the Schedule C-mapped export produces a single PDF with per-trip rows and totals.
5. Reconcile odometer to log. Pull your earliest and latest service receipts of the year — that’s your independent odometer corroboration. Total miles minus business miles = personal miles. The numbers should reconcile cleanly.
6. Prepare a cover letter. Index every document to the IDR’s numbered list. Cite §274(d) and Treas. Reg. §1.274-5T(c)(2)(ii)(A) explicitly. Note that your records are contemporaneous and made at or near the time of each use.
7. Send via certified mail with return receipt (or the IRS Documentation Upload Tool if available). Keep originals. Do not annotate documents with settlement-privilege markings — the IRS rejects them.
8. Save proof of delivery. Tracking number, return receipt, and a complete copy of what you sent. If the examiner asks for follow-up, you’ll need it.

The 30/30/30/90-day timeline you cannot afford to miss

Every audit moves through the same procedural rails. The dates that matter:

Event	Window	Statutory basis	Extendable?
Initial CP2000 / Letter 566 / Letter 2202	30 days to respond	Administrative	Yes (by phone)
Form 4564 IDR	30 days standard	IRM 4.46.4	Yes (request from examiner)
Letter 525 (30-day letter + RAR) — protest to Appeals	30 days	Administrative	Usually one extension
Letter 3219 / 531 Notice of Deficiency — Tax Court petition	Exactly 90 days (150 if outside the US)	IRC §6213(a)	No — statutory, not IRS-extendable
Audit reconsideration	Any time while tax remains unpaid	IRC §6404(a)	N/A

The 90-day Notice of Deficiency is the only deadline that can permanently end your options. Miss it and the IRS assesses the deficiency, you lose the pre-payment Tax Court forum, and your only remaining route is to pay in full and sue for refund in U.S. District Court or the Court of Federal Claims. The 90 days run from the date on the notice, not the date you receive it. Weekends count. A timely USPS postmark counts as filing.

Six losing logs (and one winning one)

The Tax Court has been consistent for two decades about what doesn’t work. A small library of cases tells the story.

Velez v. Commissioner, T.C. Memo. 2018-46. An Ohio attorney claimed 34,136 business miles in 2012 — a $29,693 deduction — supported by two reconstructed logs prepared after the audit began. The court disallowed the entire deduction and sustained the 20% §6662 penalty. The opinion noted that any written evidence “has greater value the closer in time it relates to an expenditure or use.”

Royster v. Commissioner, T.C. Memo. 2010-16. A pro se taxpayer kept a log that recorded only beginning and ending odometer readings each day — no destinations, no business purpose. The court disallowed his entire mileage deduction across multiple years and imposed the accuracy-related penalty. Total miles without trip detail is not substantiation.

Garza v. Commissioner, T.C. Memo. 2014-121. The taxpayer claimed over 40,000 business miles based on annotations in a calendar — no specific destinations, no business purpose, no times. The court held that “the Court must heed the strict substantiation requirements of section 274(d)” and disallowed the deduction. A calendar alone is not a log.

DeLima v. Commissioner, T.C. Memo. 2012-291. The taxpayer’s records were allegedly lost or stolen; she offered two service invoices and a police report. The court acknowledged she used the vehicle for business but disallowed the deduction anyway because Cohan-style estimation is unavailable under §274(d). Even sympathetic facts cannot rescue missing records.

Khan v. Commissioner, T.C. Summ. Op. 2025-5. Recent reaffirmation — a small business owner offered generalized explanations and reconstructed spreadsheets. The court explicitly held that “because petitioners failed to satisfy the substantiation requirements of section 274(d) and the rules of section 6001, we cannot apply the Cohan rule to estimate the business use of the automobile.” Note: this is a Summary Opinion under §7463 and is not precedential, but the reasoning tracks the published cases.

Craddock v. Commissioner, T.C. Summ. Op. 2023-4. The taxpayer kept a log for his Ford F-150 that listed dates, locations, and purposes — but failed to separate business from personal use and contained an entry placing him in two states on the same day. The court found the log internally inconsistent and disallowed every business mile, treating home-to-jobsite trips as nondeductible commuting because the home office did not qualify as principal place of business. Also non-precedential, but illustrative.

The pattern is unmistakable. Reconstructed logs, odometer-only logs, calendar-only annotations, “I lost it” defenses, and logs that contradict themselves all lose. The only thing that consistently survives is a contemporaneous record with the four §274(d) elements, corroborated by independent evidence.

Patitz v. Commissioner — the electronic-log breakthrough

The case that almost no competitor blog cites is the one self-employed drivers most need to know.

In Patitz v. Commissioner, T.C. Memo. 2022-99 (Sept. 27, 2022), a married couple lost most of their pre-2018 employee business expense and Schedule C deductions because their other records had been destroyed in a hurricane. The husband, however, had kept a contemporaneous electronic mileage log. The Tax Court allowed his vehicle mileage deduction because the electronic log was contemporaneous, his testimony was credible, and the records met the substantiation requirements of §274(d).

The opinion is now routinely cited inside the Tax Court — Craddock invoked Patitz directly for the proposition that the taxpayer must “first prove that vehicle mileage arises from deductible business-related travel rather than nondeductible commuting.” Inside the doctrine, Patitz functions as the answer to “what does winning look like?” An electronic log made at or near the time of each trip, kept consistently, integrated with corroborating evidence, and presented with credible testimony.

That is the standard EveryLastMile’s iOS app is built to meet automatically. On-device GPS captures the route. The timestamp is the operating system’s, not the user’s. The business purpose is tagged per trip. The export maps to Schedule C Line 9. The data does not leave your device unless you choose to share it. Each of those design choices addresses a specific argument an examiner might raise about reliability or authenticity. (For the foundational record-keeping framework, see our complete guide to tracking mileage for taxes.)

Appeals Office strategy

If the examiner won’t move, the IRS Independent Office of Appeals is your next stop. Renamed in 2019 under the Taxpayer First Act, Appeals is statutorily independent from the examination function. Its mandate is to resolve disputes “without litigation on a basis which is fair and impartial to both the Government and the taxpayer.”

Appeals officers are uniquely empowered to weigh hazards of litigation — the realistic probability either side would lose in court. That allows partial settlements (60/40, 50/50, even 80/20) that a revenue agent cannot offer. For fact-heavy disputes like mileage substantiation, hazards-of-litigation analysis is the lever that lets a difficult case settle.

You request Appeals by filing a protest within the 30-day window of the Letter 525:

• Form 12203 (Small Case Request) — used when total proposed tax and penalty for each tax period is $25,000 or less. One page, list each disputed issue with a brief reason.
• Formal written protest — required if any tax period exceeds $25,000. Must include identification, a list of issues, your factual and legal arguments, and a signed perjury declaration.

Typical Appeals resolution timeline: 6–12 months for a single-issue mileage case; longer for complex field-audit appeals. Most cases that go to Appeals settle; the Office’s own data has historically shown settlement rates well above 80%.

Tax Court options — §7463 small case vs. regular

If Appeals fails, your remaining pre-payment forum is the United States Tax Court, reachable only by filing a petition within 90 days of the Notice of Deficiency.

You have two procedural paths.

Small tax case (§7463 “S case”) — available when the deficiency, including penalty, for any one taxable year is $50,000 or less. The filing fee is $60. Procedure is informal: relaxed evidence rules, simpler pleadings, often resolved in a single half-day hearing. The catch: §7463(b) provides that S-case decisions “shall not be reviewed in any other court and shall not be treated as a precedent for any other case.” You cannot appeal. Neither can the IRS. These cases are issued as Summary Opinions (T.C. Summ. Op.). Khan and Craddock above are both Summary Opinions.

Regular Tax Court case — formal procedure, Federal Rules of Evidence apply, written and oral pretrial procedure, longer timeline, and the decision is appealable to the appropriate Circuit Court of Appeals. Choose this if your case turns on a legal argument that may benefit from precedent or where preserving appellate rights matters.

For most self-employed drivers with a single-year mileage dispute under $50,000, the small case procedure is faster, cheaper, and conserves resources. For a multi-year dispute, a serious legal issue, or any case where appellate review matters, choose the regular path.

A few representation notes. An Enrolled Agent or CPA can represent you before the IRS at every administrative level, and in Tax Court if they pass the non-attorney admission exam. A tax attorney is the only professional with true attorney-client privilege — including in criminal matters where the §7525 federally authorized practitioner privilege does not apply. Form 2848 (Power of Attorney) is how you bring a representative into the conversation; it stays in effect until revoked.

Worked example 1 — Maria, the pre-audit driver

Maria is a freelance graphic designer in Austin. In 2026 she’ll drive an estimated 14,000 business miles visiting clients and printers. At 72.5¢/mile that’s a $10,150 deduction. She files Schedule C. She also has a 120-square-foot dedicated home office in a 1,200-square-foot apartment.

Her audit-defense build:

• EveryLastMile installed on her iPhone in January. Every trip auto-captured by GPS with timestamp, route, and odometer interpolation.
• Business purpose tagged per trip — “Client visit: Acme Co. logo review” — not “business”.
• A monthly mid-month export reconciled against her Google Calendar.
• January 1 oil change with the dealer noting odometer at 38,420. Year-end oil change with odometer at 53,210. Total annual miles: 14,790. Business miles per ELM: 14,012. Business-use percentage: 94.7%.
• Home office documented with floor plan, photographs, and Form 8829 — establishing principal place of business under §280A(c)(1)(A), so all client trips are deductible per Rev. Rul. 99-7.
• Insurance declarations updated to note business use.

If Maria is audited, her response to an IDR is a single indexed PDF: the ELM Schedule C export, two oil-change receipts, her calendar export, the home-office floor plan, and the insurance declarations. The four §274(d) elements are present in every line. The §6662 penalty conversation never starts. Her preparation cost: about 90 seconds per trip, automated.

Worked example 2 — David, the mid-audit driver

David is a real estate agent in Phoenix who claimed 22,000 business miles in 2024 — a $15,400 deduction at the then-current rate. He kept a calendar but no formal log. In April 2026 he opens a CP2000 followed by Letter 525 proposing to disallow the entire mileage deduction.

His exposure if he does nothing:

His response strategy:

• File Form 2848 immediately and bring in an Enrolled Agent.
• Respond to the IDR within 30 days. Submit the contemporaneous calendar entries, MLS access logs showing property visits on each claimed date, client texts and emails confirming showings, oil-change receipts establishing total annual miles, and 1099-NECs from his brokerage.
• Acknowledge that the original Schedule C entry was rounded, and propose an adjusted figure based on the documents actually available. Drop the 22,000 to the defensible 17,400.
• File a §6664(c) reasonable-cause letter explaining the good-faith use of his calendar and MLS records as a substantiation system, and note that he has installed EveryLastMile on his iPhone for 2026 forward (which our mileage tracking guide for real estate agents recommends as the industry standard).
• If the examiner won’t move, file a Form 12203 protest within the 30-day Letter 525 window to take the case to Appeals.

Realistic outcome with competent representation: most of the 17,400 miles allowed, the §6662 penalty waived under §6664(c), residual exposure under $2,000. Without representation and contemporaneous corroboration, the original $8,233 stands.

How automatic tracking creates audit-defensible records

The case law and the regulations point in the same direction. The records that win in Tax Court share four properties:

1. Made at or near the time of each trip — Treas. Reg. §1.274-5T(c)(2)(ii)(A).
2. Cover all four §274(d) elements — amount, time, place, and business purpose.
3. Internally consistent — the trips reconcile with odometer readings, calendar entries, and client records.
4. Credible on their face — a contemporaneous timestamp the user did not type, integration with other business records, and a presentation that an examiner can verify.

Automation is not a luxury; it is the cheapest path to satisfying every one of those properties without ongoing effort. EveryLastMile’s iOS app uses on-device GPS to capture each trip, system-clock timestamps that establish contemporaneity, per-trip business purpose tagging, and a Schedule C-mapped export that produces an audit-ready PDF. Route data stays on your device — there is no cloud upload unless you choose to share it — which matters both for privacy and for the integrity story you tell an examiner.

The §274(d) standard was written in 1985. The Tax Court has been applying it the same way ever since. The difference today is that the standard is no longer hard to meet. It just has to be met before anyone asks.

Frequently asked questions

What triggers an IRS mileage audit?

The most common triggers are 1099-NEC mismatches (which auto-generate CP2000 notices), high deductions relative to gross receipts, round-number expenses, repeated Schedule C losses, home office combined with very high mileage, and industry codes flagged by the IRS as elevated risk (cash-intensive businesses, real estate, rideshare, construction subs). Mileage itself is a frequent secondary issue once an audit opens.

Will the IRS accept a reconstructed mileage log?

Almost never. Velez, Khan, and a long line of Tax Court cases have rejected reconstructed logs as failing the 'made at or near the time' requirement of Treas. Reg. §1.274-5T(c)(2)(ii)(A). Reconstruction may rescue a portion of the deduction in limited cases, but never with the credibility of a contemporaneous record.

How far back can the IRS audit my mileage deduction?

Three years from the return filing date under §6501(a). Extended to six years under §6501(e) if you omitted more than 25% of gross income. Unlimited for fraudulent or unfiled returns under §6501(c).

What is IRS Form 4564, and how do I respond?

Form 4564 is the Information Document Request — the formal written request used by IRS examiners to ask for specific records. Standard response time is 30 days. Respond by indexing every document to the IDR's numbered list, citing §274(d) compliance, and sending certified mail with return receipt.

What is IRS Letter 525, and what's the deadline?

Letter 525 is the '30-day letter' — sent at the conclusion of a correspondence audit with the Revenue Agent's Report (Form 4549) attached. You have 30 days to either agree or file a written protest with the Independent Office of Appeals.

Does the Cohan rule let me estimate mileage if I don't have records?

No. Cohan v. Commissioner allows estimation for many deductions, but §274(d) overrides Cohan for travel and listed property (which includes passenger automobiles under §280F(d)(4)). The Tax Court has rejected Cohan-style estimation for vehicle expenses in Sanford, DeLima, Khan, and many other cases.

What is the 20% accuracy-related penalty on a disallowed mileage deduction?

Under §6662(a), the IRS adds 20% of the underpayment when the understatement is 'substantial' — the greater of $5,000 or 10% of the correct tax — or when negligence applies. For a fully disallowed mileage deduction, both prongs typically apply. First-Time Abatement does not apply to §6662; only §6664(c) reasonable cause can defeat it.

Can I use a reasonable cause defense under §6664(c) if I relied on a GPS app?

Potentially yes. §6664(c) waives the §6662 penalty when you show reasonable cause and good faith. Good-faith reliance on a contemporaneous tracking system that captures the four §274(d) elements is precisely the kind of effort Treas. Reg. §1.6664-4(b) identifies as relevant. The defense is fact-specific and rarely automatic.

What is the burden of proof in a mileage audit, and when does it shift under §7491(a)?

Default: the taxpayer bears the burden. §7491(a) shifts it to the IRS only if you introduce credible evidence, meet the Code's substantiation requirements, maintain required records, and cooperate with reasonable IRS requests. For mileage cases, you can almost never reach the shift without also meeting §274(d) — at which point the burden shift is largely moot.

Should I file in Tax Court as a small case under §7463?

If your total deficiency including penalty is $50,000 or less per year, the small case procedure offers informal proceedings, a $60 filing fee, and faster resolution. The trade-off: §7463(b) bars appeal and removes precedential value. Choose it for a routine factual dispute; choose regular Tax Court for legal issues or multi-year cases.

Can I deduct mileage from my home if I have a home office?

Yes — if your home office qualifies under §280A(c)(1)(A) as your principal place of business (exclusive and regular use, principal place where you conduct trade or business). Rev. Rul. 99-7 then treats trips from home to any other work location as deductible business mileage. Without a qualifying home office, the first trip of the day and the last trip home are typically nondeductible commuting.

Do GPS mileage tracker apps satisfy the IRS contemporaneous-record rule?

Yes, when the app captures the four §274(d) elements (amount, time, place, business purpose) and the entry is made at or near the time of the trip. Patitz v. Commissioner, T.C. Memo. 2022-99, is the most prominent case allowing a deduction based on a contemporaneous electronic log. The integrity of the timestamp and the per-trip business purpose tagging are what give the record its weight.

What is audit reconsideration?

Audit reconsideration (IRS Pub 3598; IRM 4.13) allows you to ask the IRS to reopen an examination after assessment, while the tax remains unpaid, if you have new information, never received the original notice, or moved. It is not a substitute for the 90-day Tax Court window but is the most useful tool for taxpayers who defaulted on prior notices.

What's the difference between a 30-day letter and a 90-day Notice of Deficiency?

The 30-day letter (Letter 525) is the administrative end of an audit — it offers you the Appeals route. The 90-day letter (Letter 3219 or 531, the Statutory Notice of Deficiency) is the legal end — your only ticket to pre-payment Tax Court review, with a non-extendable 90-day window under §6213(a).

How do I challenge an IRS auditor's mileage disallowance at the Appeals Office?

File a protest within the 30-day window of the Letter 525. Use Form 12203 if the dispute is $25,000 or less per period; submit a formal written protest if larger. Lead with §274(d) compliance evidence and a hazards-of-litigation argument — Appeals officers can compromise based on the realistic probability of an IRS loss in court, a flexibility the examiner does not have.