A driving log is a record of when, where, and how far you drive
A driving log is a written or digital record that documents your trips: the date, time of day, starting location, ending location, miles driven, and the purpose of the trip. Some logs also track fuel costs, maintenance, or passenger details. The format ranges from a straightforward notebook entry to a spreadsheet to a dedicated app that uses your phone's GPS.
You keep a driving log for one of three main reasons: to track mileage for tax deductions, to monitor your own driving habits and safety, or because your insurance company or employer requires it. The content and detail level depend on why you are logging. A tax-deduction log looks different from a safety log, and an insurance-required log has its own rules.
Key Takeaways
- A driving log records trip date, time, location, mileage, and purpose — the exact details required depend on whether you are tracking taxes, safety, or insurance.
- For tax deductions, the IRS requires contemporaneous written records that show business miles separately from personal miles, and you must keep receipts for fuel and maintenance.
- Insurance companies may require logs to monitor high-risk drivers or to lower premiums for low-mileage or safe drivers, and the log format is usually specified by the insurer.
- Employers often require logs for company vehicles or reimbursement claims, and the log becomes part of your employment record and may be audited.
- Digital logs with GPS or timestamp features are harder to dispute than handwritten ones, but handwritten logs are still legally valid if they are detailed and consistent.
Driving logs for tax deductions
If you use your vehicle for business — whether you are self-employed, a contractor, or an employee claiming unreimbursed work expenses — the IRS allows you to deduct either actual expenses or a standard mileage rate. To claim either method, you must document business miles separately from personal miles using a contemporaneous written record. "Contemporaneous" means you write it down at or near the time of the trip, not weeks later from memory.
Your log must show the date, starting and ending locations (or the round-trip distance), miles driven, and the business purpose of the trip. A note like "client meeting in Portland, 47 miles" is sufficient. The IRS does not require you to log every personal trip, only the business ones. However, if you are audited, the IRS will compare your logged business miles to your total annual miles to check whether the ratio is reasonable. If your log shows 10,000 business miles but your odometer shows 12,000 total miles, that is plausible. If it shows 10,000 business miles and 11,000 total, the auditor will question whether you are underreporting personal use.
Keep your log in a format you can produce if audited — a notebook, a spreadsheet, or a mileage-tracking app. The IRS does not mandate a specific format, but the log must be clear enough that someone else could read and verify it. Handwritten logs are acceptable. Photographs of your odometer at the start and end of a trip strengthen your record, though they are not required.
Driving logs required by insurance companies
Some insurers require or encourage driving logs as part of a usage-based or telematics program. These programs monitor how much you drive, when you drive, and sometimes how safely you drive. Low-mileage drivers, young drivers, or drivers with recent violations may be asked to keep a log or install a device that tracks trips automatically.
If your insurer requires a log, they will usually specify the format and what information to record. Some insurers provide a printable template or a mobile app. The log typically captures date, time, distance, and sometimes destination type (commute, personal errand, long trip). The insurer uses this data to calculate your premium or to verify that you meet the terms of a discount program.
Unlike tax logs, insurance logs are often reviewed by the insurer itself, not by you alone. If you are dishonest — logging fewer miles than you actually drive, for example — and the insurer discovers the discrepancy through other means (such as a claim or a device that contradicts your log), you may face premium increases, policy cancellation, or denial of a claim. Stick to what you actually drove.
Driving logs for employers and reimbursement
If you drive a company vehicle or use your personal vehicle for work and seek mileage reimbursement, your employer will likely require a driving log. The employer uses the log to verify that the miles you claim are legitimate business miles and to calculate what they owe you. Some employers reimburse at the IRS standard mileage rate; others use a rate they set internally.
An employer's log requirement is often stricter than the IRS requirement because the employer is paying you directly and wants a clear audit trail. Your log should show the date, starting and ending locations, miles, and the business purpose. Some employers also ask for the names of clients visited or the type of work performed. Keep the log contemporaneously — do not wait until the end of the month to fill it in, because employers are skeptical of retroactive logs.
If you submit a reimbursement claim without a log, or with a log that is vague or inconsistent, your employer may deny the claim or ask you to provide additional documentation. If you are a regular user of a company vehicle, the employer may audit your logs periodically to may support accuracy. Falsifying a log to claim reimbursement for miles you did not drive is considered fraud and can result in termination.
Digital logs versus handwritten logs
Digital logs — whether in a spreadsheet, a dedicated app, or a telematics device — have advantages and disadvantages compared to handwritten logs. A digital log with GPS or automatic timestamp features creates a record that is harder to alter or dispute. If you use an app that logs your trip automatically based on your phone's location, the timestamp and distance are generated by the app, not by you, which makes the record more credible to an auditor or insurer.
Handwritten logs are still legally valid for tax purposes and for most employer reimbursement claims, but they are easier to challenge. An auditor may question whether you wrote the entry at the time of the trip or filled it in later. To strengthen a handwritten log, write in pen (not pencil), date each entry, and be consistent in your format and detail level. Some people photograph their odometer before and after a trip to create a time-stamped record that corroborates their log entry.
For insurance purposes, the insurer will specify whether they accept handwritten logs or require a digital submission. Many insurers now provide or require a mobile app that logs trips automatically. If you are given a choice, a digital log is usually the safer option because it is harder to dispute and requires less manual effort.
Common mistakes in driving logs
The most common mistake is logging trips long after they happen. If you wait a week to fill in your log, you will forget details, and an auditor will assume you are guessing. Write your log the same day as the trip, or use an app that logs automatically. Another mistake is being vague about the purpose. "Business trip" is weaker than "client meeting with ABC Corp in Portland." The more specific you are, the more credible your log looks.
A third mistake is mixing business and personal miles in a single trip without separating them. If you drive to a client meeting and then stop at the grocery store on the way home, log only the miles to and from the client meeting as business miles. The grocery stop is personal. Some people try to claim the entire trip as business, which raises red flags during an audit.
A fourth mistake is failing to keep supporting documents. If you claim 5,000 business miles in a year, the IRS may ask for receipts for fuel, maintenance, or insurance to verify that your mileage claim is consistent with your actual vehicle expenses. Keep fuel receipts, maintenance invoices, and insurance bills alongside your log.
How to set up a driving log
If you are logging for tax purposes, start with a straightforward format: date, starting location, ending location, miles, and business purpose. You can use a notebook, a spreadsheet, or a free app like Stride Health's mileage tracker or Everlance. The format matters less than consistency and detail. If you switch formats mid-year, make sure the new format captures the same information as the old one.
If you are logging for an employer, ask your employer for their template or preferred format. Do not assume your own format will be accepted. If you are logging for insurance, use the format or app your insurer specifies. If you are logging for your own safety or habit tracking, you have full flexibility — include whatever information helps you understand your driving patterns.
Start your log before you need it. If you wait until tax time to begin logging, you will have no record of the miles you drove earlier in the year. If you are a contractor or self-employed, begin logging on January 1. If you are an employee seeking reimbursement, start logging as soon as you begin using your vehicle for work.
Frequently Asked Questions
Do I have to keep a physical copy of my driving log, or is digital okay?
Digital logs are acceptable for tax purposes and most employer reimbursement claims. The IRS does not require a specific format. However, you must be able to produce the log if audited, so keep it backed up and accessible. For insurance purposes, follow your insurer's requirements — some accept digital logs, others require a specific app or format.
What if I forget to log a trip?
For tax purposes, a missing trip weakens your overall record but does not invalidate the log. If you remember the trip later, add it with a note that it was recorded retroactively. For employer reimbursement, a missing trip usually means you cannot claim those miles — employers are strict about contemporaneous records. For insurance, a missing trip is unlikely to matter unless the insurer discovers you drove more than your log shows.
Can I use my car's built-in trip computer or GPS history instead of a manual log?
For tax purposes, the IRS prefers a written record that you maintain, not a device log alone, because you control the content and can explain the business purpose. However, a device log can support your written log. For insurance, many insurers now use GPS or app-based tracking, which they prefer to manual logs. Check with your insurer about what they accept.
What happens if I am audited and my log does not match my actual mileage?
If your log shows significantly fewer miles than your vehicle's odometer or fuel consumption suggests, the IRS may disallow part or all of your mileage deduction. If your log shows more miles than is plausible, the same result occurs. Keep supporting documents like fuel receipts and maintenance records to help explain the discrepancy.
Do I need to log personal trips, or only business trips?
For tax purposes, you only need to log business miles. You do not need to record every personal trip. However, the IRS may ask you to account for your total annual mileage to verify that your business-mile claim is reasonable. For insurance or employer purposes, follow the specific requirements you were given — some programs ask for all trips, others only work-related ones.