How to Decide Whether Your Business Needs a Simple Mileage Log Before Tax Season

If you drive your personal vehicle for business purposes, the IRS allows you to deduct those miles. The standard mileage rate changes periodically, but even at modest rates, a few hundred miles a month adds up to a meaningful deduction over a year. The catch is that the IRS requires contemporaneous records, meaning you need to log trips as they happen, not try to reconstruct them from memory in April.

Many small-business owners skip this entirely until their accountant asks for mileage totals and they realize they have nothing useful to show. This article walks you through a simple decision process so you can figure out whether a mileage log is worth setting up, what form it should take, and how much effort is actually involved.

First, Ask Whether You Have Any Qualifying Trips

Not all driving qualifies. The IRS does not allow a deduction for commuting from home to your regular place of business. However, trips that typically do qualify include driving to meet a client, traveling between job sites, picking up supplies for a job, visiting a bank or post office for business purposes, and driving to a business-related appointment.

If you are an owner-operator who drives a dedicated work vehicle and never uses it personally, your situation is different from someone who shares a single car between personal errands and client visits. For the shared-vehicle situation, a log is the only clean way to separate personal from business use.

A simple first step: think back over the last two weeks and count how many trips you made that were clearly for business. If the honest answer is more than a handful, a log is probably worth keeping.

What a Valid Mileage Log Actually Needs

The IRS specifies four pieces of information for each business trip: the date, the destination or general route, the business purpose, and the number of miles. That is it. You do not need a sophisticated system. A small notebook kept in your vehicle, a note in your phone, or a simple spreadsheet updated daily will satisfy the requirement if it captures those four fields consistently.

For example, a hypothetical log entry might look like this: "March 14 / Drive to Riverside Supply Co. / Pick up paint for Henderson job / 18 miles." That entry takes under thirty seconds to record and is exactly what a tax professional or auditor would want to see.

At the end of the year, you total the business miles, multiply by the current IRS standard mileage rate, and that figure becomes your deduction. Alternatively, you can use the actual expense method, which tracks fuel, maintenance, insurance, and depreciation proportionally, but that approach is more complex and usually only advantageous if you drive a lot in an expensive vehicle. Most small-business owners find the standard mileage rate simpler and sufficient.

Evaluating Your Logging Options

You have three realistic choices, each with a different cost and effort tradeoff.

A paper log. A small notebook or a printed mileage log template costs almost nothing. The downside is that paper logs get lost, left at home, or filled out inconsistently. If you are disciplined and the vehicle is always nearby, paper works fine.

A spreadsheet. A shared Google Sheet or Excel file lets you log from your phone and gives you a running total automatically. This works well for owners who already live in spreadsheets and want one place to store the data. Setup takes under an hour.

A mileage tracking app. Several apps automatically detect when you are driving and let you swipe trips as business or personal after the fact. Some use GPS to calculate distances. These tools typically cost a few dollars per month or offer a free tier with limitations. The main benefit is that they remove the habit problem entirely. The tradeoff is a small ongoing cost and the need to review and categorize trips regularly. If you routinely forget to log manually, an app may pay for itself in recovered deductions within the first month.

There is no universally correct option. The best system is the one you will actually use every week.

A Practical Way to Start Today

If you decide a log is worth keeping, the fastest way to begin is to record your odometer reading today, note the date, and commit to logging every business trip for the next 30 days. After 30 days, look at what you captured. Multiply those miles by the current standard mileage rate published on IRS.gov and see what the annualized deduction would look like. That number tells you whether the habit is worth sustaining.

For example, a hypothetical owner who drives 200 business miles per month would log 2,400 miles over a year. At a standard rate in a common range, that could represent several hundred dollars in deductions. Whether that feels significant depends on your overall tax situation, which is a conversation to have with your tax preparer, not something this article can determine for you.

What to Do If You Have Already Lost Part of the Year

If it is already mid-year and you have no records, you have a few options. You can start now and capture the remaining months accurately. A partial-year log with solid records is better than nothing and is a legitimate deduction for the months covered.

Some tax preparers will also accept a reconstruction based on calendar entries, client invoices, or job records if you can support the trips with other documentation. However, a reconstructed log carries more audit risk than a contemporaneous one, and you should discuss that tradeoff directly with your preparer rather than relying on informal advice.

Going forward, a simple habit established before next January protects the full year.

The Bottom Line

A mileage log is one of the lowest-effort deductions available to small-business owners who drive for work. The recordkeeping requirement is straightforward, the tools range from free to a few dollars a month, and the setup time is under an hour regardless of which method you choose. The main risk is not that the log is complicated, it is that it never gets started. Deciding to set it up before your next business trip is all the preparation that is actually required.