Tax deduction tracker: how to log write-offs all year

Most freelancers and side-business owners do not lose deductions because they do not qualify for them. They lose them because in March nobody can remember the 14 client drives from last June, the phone bill that was half business, or the software renewal that came out of a personal card. A tax deduction tracker fixes that: one place where every deductible mile and expense goes in on the day it happens, with the proof attached. This guide shows what to track, what the IRS expects you to keep, a worked year with the tax it saves, and how to set it up in an app or a spreadsheet in about ten minutes.

This is general information for US sole proprietors and single-member LLCs filing Schedule C, not tax advice. Your own figures depend on your bracket, your state and your situation, so confirm anything large with a tax professional.

What a tax deduction tracker needs to record

Every entry, whether it is a trip or a purchase, needs enough detail that someone else could understand it a few years later. For expenses that means:

• Date the money left your account.
• Amount, and the business share if the item is part personal (a phone, internet, a car).
• Category that matches a Schedule C line: advertising, car and truck, contract labor, insurance, legal and professional, office expense, supplies, travel, meals, utilities and so on.
• Who you paid and why, in a few words: "Canva Pro, client social posts".
• The receipt, as a photo or a PDF, linked to the entry.

For mileage, IRS Publication 463 asks for the date, the miles, the destination and the business purpose of each trip. "Client meeting, 1420 Oak St, 18 mi" is a complete entry; "work, 18 mi" is not. A log written at the time is far stronger than one reconstructed from a calendar a year later.

What counts, with the rules people trip over

On mileage, 2026 has two standard rates: 72.5 cents a mile for business miles from January 1 to June 30 and 76 cents from July 1 to December 31. Our 2026 mileage deduction guide covers who can claim it and standard rate versus actual expenses. Because the rate changes mid-year, your log must keep the date of every trip, not just a yearly total.

A worked year: what tracking is actually worth

Take a freelance designer who works from home, drives to clients and keeps a tracker all year. These are the deductions it captures:

Each dollar of deductions lowers two taxes for a sole proprietor:

• Income tax at your marginal rate. In the 22% bracket: $7,002 × 22% = $1,540.
• Self-employment tax of 15.3% on 92.35% of net earnings: $7,002 × 92.35% × 15.3% = $989.

Together that is about $2,530 less tax for the year, before any state income tax. (This is simplified: the deduction for half of self-employment tax and the qualified business income deduction change the exact figure slightly, but the order of magnitude holds.) Miss half of the mileage and the phone share because nobody logged them, and roughly $1,000 of that saving disappears.

How long to keep the records

The IRS's general rule is to keep records that support a return for 3 years from the date you filed it. The period is 6 years if you under-report income by more than 25%, and 7 years for a loss from worthless securities or a bad debt. Records for business property are kept until the period runs out for the year you sell or dispose of it. Publication 463 also asks for documentary evidence, such as receipts, for lodging and for any other travel or meal expense of $75 or more. A photo of the receipt saved with the entry is fine, as long as it is legible.

Set it up: app or spreadsheet

Option 1: a phone app

An app wins on mileage, because the phone is in the car with you. Our free Mileage & Tax Expense Tracker records trips by GPS with one tap, lets you mark each one business or personal, logs deductible expenses with notes, and exports an annual summary for your accountant. It is on iPhone and Android with no subscription. If you compare options first, our roundup of the best free mileage tracker apps covers the trade-offs between GPS, automatic and manual logging.

Option 2: a spreadsheet

A spreadsheet works well for expenses, especially if most of them arrive as card or bank transactions you can paste in. Use one row per expense with columns for date, category, payee and purpose, amount, business %, deductible amount and a receipt link. The deductible column is simply amount × business %, and a SUMIFS on category gives you each Schedule C line. Our small business income and expense spreadsheet guide has the full layout and formulas.

Many people use both: the app for miles, the sheet for everything else, and one total at year end.

A ten-minute weekly routine

1. Open the tracker every Friday and classify the week's trips as business or personal.
2. Snap any paper receipts in your wallet or the car and attach them to their entries.
3. Scan your business card and bank account for the week and add anything missing.
4. Once a month, check the totals against your statements so nothing is counted twice.
5. Each quarter, use the profit figure to size your estimated tax payment.

Bills that recur every month, like software, phone and insurance, are easiest to catch if they are already on a calendar. How to organize bills shows how to keep due dates and amounts in one place, which doubles as a checklist of recurring business costs at tax time.

Bottom line

A tax deduction tracker is worth thousands of dollars a year for most self-employed people, and nearly all of that value comes from writing things down at the time. Log trips with date, miles, destination and purpose, record the business share of mixed-use costs, keep the receipt with the entry, and keep the records for at least three years.