IRS Insider: Why Missing Mileage Logs Matter More Than You Think

Most small business owners don’t mean to skip mileage logs. It’s just one of those tasks that feels easy to “remember later.”

You tell yourself you’ll track it next week… and before you know it, the year’s almost over and your mileage is a total mystery.

But here’s the truth: missing mileage logs are one of the most common—and costly—mistakes I saw when auditing small businesses inside the IRS.

Let’s talk about why they matter, what the IRS actually expects (straight from the Internal Revenue Manual), and how to fix it before it costs you money.

---

1. Mileage Isn’t Guesswork—It’s Evidence

The IRS doesn’t allow mileage deductions based on estimates or memory.Every mile you claim must be backed by contemporaneous records—meaning records made at or near the time of travel.

That’s not me being strict—that’s directly from IRS IRM 4.10.7.3.8 (Evaluation of Evidence) and IRM 4.10.5.9.7 (Mileage Logs and Travel Records).

In plain English?

“The taxpayer must have sufficient records to substantiate the amount, time, place, and business purpose of travel.”

If you can’t show that, the deduction can be reduced—or denied completely.

---

2. The Standard the IRS Uses

When an IRS agent reviews your mileage claim, they’ll look for four specific elements:

1. Date of each trip

2. Destination (from/to)

3. Business purpose

4. Miles driven

If you provide a total like “10,000 miles for business,” that’s not enough.You need to show how you got there.

Even a handwritten notebook, Excel sheet, or app printout will do—as long as it’s consistent and believable.

---

3. Why Mileage Records Get Audited So Often

Mileage deductions are easy to inflate and hard to verify—so they’re an automatic audit target.

Inside IRM 4.10.4.3.3 (Audit Techniques for Business Expenses), agents are instructed to test “reasonableness” by comparing mileage claimed to:

• The type of business you’re in

• The number of clients or locations visited

• Your total gross income

If your mileage looks high compared to your income or industry, it raises questions.

And if you don’t have documentation? The IRS assumes the worst.

---

4. What Happens When You Don’t Have Logs

Here’s the part most people don’t realize: the IRS can disallow 100% of your mileage deduction if your logs are missing or unreliable.

Even if it’s obvious that you used your vehicle for business, you still lose the deduction without records.

I once audited a self-employed contractor who claimed 22,000 miles but had no log. We allowed only 2,000 miles—the few he could verify through invoices and fuel receipts. That one mistake cost him over $3,000 in taxes and penalties.

---

5. What Counts as “Good Enough” Documentation

You don’t need perfection—you just need consistency.

Acceptable proof can include:

✅ A mileage app (like MileIQ or Everlance)

✅ A paper logbook or Excel sheet

✅ Calendar entries tied to client meetings

✅ Receipts or invoices that support specific trips

The IRS allows “reasonable reconstruction” when some data is missing—but only if it’s clear you kept regular records most of the year.

---

6. How to Rebuild a Missing Log (If You’re Behind)

If your mileage logs are incomplete, you can reconstruct them—carefully.

Here’s how:

1. Pull your calendar, invoices, and client list to identify travel days.

2. Use Google Maps or similar tools to estimate distances between destinations.

3. Record business purpose for each trip (meeting, delivery, supply run, etc.).

4. Keep documentation (emails, texts, receipts) that align with those trips.

Label the sheet “Reconstructed Log for [Year].”It’s not perfect, but it’s far better than nothing—and the IRS (per IRM 4.10.7.3.8.2) will consider it if it’s logical and consistent.

---

7. The Florida Reality: Driving Adds Up

For Central Florida solopreneurs and contractors, mileage is often your biggest overlooked deduction.

Between client meetings in Mount Dora, vendor pickups in Apopka, and events in Orlando, you can easily rack up thousands of deductible miles.

But without logs, those miles disappear from your tax return—and from your profit.

---

8. How Zero Fluff Books Helps

We know mileage tracking can feel tedious, which is why we include a free, ready-to-use Mileage Log Template for all our clients.

👉 Download your free Mileage Log Template here 

It’s Excel-based, IRS-compliant, and built to match IRM 4.10 documentation standards—so you can track miles once a week and stay compliant all year long.

We also help clients recreate missing mileage records for audit prep and cleanup projects.

👉 Learn about our Cleanup & Audit Support Services 

---

Mileage isn’t just a number—it’s a deduction you have to defend.If you can’t prove it, you can’t keep it.

Keep clean logs now, and you’ll save money, stress, and credibility later.