Why you need a mileage record and what it proves

The IRS requires you to keep a contemporaneous mileage log — a record made at or near the time you drive — if you want to deduct vehicle expenses on your taxes or get reimbursed by an employer. A mileage log is not optional; it is the only evidence the IRS accepts. A credit card statement, a calendar note, or a memory of how much you drove will not hold up in an audit.

Your log must show the date, the starting and ending odometer readings (or total miles driven), the business purpose of the trip, and the destination. "Client meeting" is enough for business purpose; "personal errands" is not deductible. The log does not have to be fancy — a notebook, a spreadsheet, or a mileage-tracking app all work equally well, as long as you create the record while the trip is fresh, not weeks later.

Employers often reimburse mileage at a standard rate set by the IRS (the rate changes yearly and varies by vehicle type and use). Self-employed people and business owners use mileage records to calculate the vehicle expense deduction on Schedule C. Either way, the log is your proof.

Key Takeaways

  • A mileage log must record the date, odometer readings or miles driven, destination, and business purpose for each trip — made at the time of the trip, not later.
  • The IRS standard mileage rate changes each year; check the current rate on IRS.gov before you calculate reimbursement or deductions.
  • A notebook, spreadsheet, or app all work; the format does not matter as long as you create the record contemporaneously.
  • Personal commutes to your regular workplace are never deductible, even if you work from home some days.
  • If your employer has a mileage reimbursement policy, follow it exactly — some policies require submission within a certain timeframe or cap the reimbursable amount.

Setting up a notebook or spreadsheet log

The simplest method is a small notebook you keep in your vehicle. At the start of each trip, write the date, your starting odometer reading, and where you are going. At the end of the trip, write your ending odometer reading and the business purpose. Subtract the starting reading from the ending reading to get the miles driven. Do this when ready after each trip, while you remember the details.

If you prefer a spreadsheet, create columns for date, starting odometer, ending odometer, miles driven (a formula can calculate this automatically), destination, and business purpose. Add a row for each trip. The advantage of a spreadsheet is that you can sort by purpose, sum miles by category, and calculate totals for tax time without rewriting anything.

Either method requires discipline: you must record every trip the day it happens. A log you fill in from memory at the end of the month will not satisfy the IRS if you are audited. Keep your notebook or spreadsheet accessible — in your car, on your phone, or in a folder you check weekly.

Using a mileage-tracking app

Apps like MileIQ, Stride Health, and others automate the process by using your phone's GPS to detect when you drive and log the mileage automatically. You then categorize each trip (business, medical, charitable, personal) and add notes about the destination or purpose. The app stores the data and generates reports you can export for tax time or send to your employer.

The main advantage is that you do not have to remember to write anything down — the app captures the trip as it happens. The main disadvantage is that some apps charge a monthly or annual fee, and you must keep the app running and your phone with you on every trip. Some apps also require an internet connection to sync data, so check the app's requirements before you commit.

If you use an app, treat it the same way you would a notebook: review the entries regularly to make sure the app categorized trips correctly and captured the right mileage. Apps sometimes misidentify short trips or log phantom miles if GPS is unreliable in your area.

What counts as deductible mileage

Business mileage includes trips to client meetings, job sites, conferences, and other work-related destinations. If you are self-employed, it includes miles driven to meet with customers or vendors. If you work for an employer, it includes miles driven on company business during the workday — but not your commute to and from your regular workplace, even if you work from home and drive to the office some days.

Medical mileage covers trips to doctor's offices, hospitals, pharmacies, and medical appointments for yourself or a dependent. Charitable mileage covers miles driven on behalf of a may have access to charity — volunteering at a food bank, for example, but not driving to donate items. The IRS publishes the deductible rate for each category each year on IRS.gov.

Personal mileage — groceries, errands, entertainment, commuting to a regular job — is never deductible. If a trip has both business and personal purposes, you can only deduct the business portion. For example, if you drive to a client meeting and then stop at the grocery store on the way home, you deduct only the miles to and from the client meeting, not the detour to the store.

Submitting mileage records to your employer

If your employer reimburses mileage, check your employee handbook or ask your manager for the reimbursement policy. Most policies require you to submit your mileage log within a certain timeframe — often 30 to 60 days after the trip — and some cap the monthly or annual reimbursement amount. Missing the important date or exceeding the cap can mean you do not get reimbursed for those miles.

When you submit, provide a summary or the full log showing the date, miles driven, and business purpose for each trip. Some employers use a standard form; others accept a spreadsheet or app export. Keep a copy of what you submit and the employer's confirmation that they received it. If the reimbursement does not appear on your next paycheck, follow up with payroll or accounting.

Mileage reimbursement from an employer is not taxable income if the reimbursement does not exceed the IRS standard rate and you substantiate the mileage with a log. If your employer reimburses you at a higher rate or does not require a log, the excess may be taxable; ask your payroll department or tax preparer.

Using mileage records for tax deductions

If you are self-employed or own a business, you deduct vehicle expenses on Schedule C (Profit or Loss from Business) when you file your tax return. You have two options: the standard mileage method or the actual expense method. The standard mileage method is simpler: multiply your total business miles by the IRS standard rate for the year. The actual expense method requires you to track fuel, maintenance, insurance, and depreciation, then calculate the percentage of those expenses that were for business use.

Most people use the standard mileage method because it requires only your mileage log and the published rate. To use it, add up all your business miles for the year (your log should already be organized this way) and multiply by the rate. The IRS publishes the rate each November for the following year on IRS.gov. For example, if the 2024 business mileage rate is 67 cents per mile and you drove 5,000 business miles, your deduction is $3,350.

You must have your mileage log ready when you file your return. If you are audited, the IRS will ask to see it. A log that is clearly dated and contemporaneous — made at the time of each trip — is much more likely to survive scrutiny than one you reconstruct from memory or other documents.

Keeping your log organized and backed up

At the end of each month, review your log and make sure every entry is complete and legible. If you use a notebook, photograph the pages or scan them into a computer file. If you use a spreadsheet, save it in at least two places — your computer and a cloud storage service like Google Drive or Dropbox. If you use an app, export your data regularly and save it to a file.

Keep your log for at least three years after you file your tax return. The IRS can audit returns from up to three years back (or longer if there is a substantial underreporting of income). If your employer asks for mileage records, keep them for as long as the employer requires — often five to seven years for payroll and reimbursement records.

Label your files clearly: "Mileage Log 2024" or "Business Mileage 2024" so you can find them quickly at tax time or if you are audited. If you switch from a notebook to an app or vice versa, make sure the transition is clear in your records — for example, "Notebook entries January–June, app entries July–December."

Frequently Asked Questions

Can I estimate mileage if I forgot to write it down for a few trips?

No. The IRS requires a contemporaneous log, which means you must record mileage at the time of the trip. If you miss a few entries, you cannot go back and estimate them. If you forget to log a trip, straightforward do not include it in your deduction or reimbursement request. Consistency and accuracy matter more than a high total.

What if I use my personal car for both business and personal driving?

You track only the business miles. Your log should show the date, miles, destination, and business purpose for each business trip. Personal trips do not go in the log at all. At tax time, you deduct only the business miles multiplied by the standard rate, not the total miles you drove.

Do I need to include the odometer reading if I use a mileage app?

No. A mileage app uses GPS to calculate distance, so you do not need to record odometer readings. However, you should still note the destination and business purpose for each trip so you have a clear record of why you drove. Review the app's entries regularly to make sure they are accurate.

What happens if I do not have a mileage log when I am audited?

Without a contemporaneous log, the IRS will disallow your mileage deduction or reimbursement claim entirely. You cannot reconstruct a log after the fact and expect it to hold up. This is why keeping a log as you drive is critical — it is your only proof.

Can I deduct mileage for a trip that was partly business and partly personal?

You can deduct only the business portion. If you drive to a client meeting and then run personal errands on the way home, you deduct the miles to the meeting and back to your starting point, not the detour. Your log should note the business purpose and destination so the split is clear.