The Mileage Tax Log Builder is a free online tool that builds a business mileage log from pasted trips, with dates, trips, and miles, totalled by month for tax records. It runs entirely in your browser, so you do not need to install anything, create an account, or share your business data with anyone. You open the page, type in your own numbers, and get a clear answer in seconds. Small business owners often do tax arithmetic by guesswork or on scraps of paper, and this tool replaces that guesswork with simple arithmetic you can check yourself.
It is made for self-employed people and employees who drive for business and claim mileage. If you run a small business, you already know that tax numbers hide inside everyday decisions. A price, a purchase, a trip, or a meal can each carry a tax consequence, and the consequence is easy to miss until the tax return arrives. This tool keeps the key numbers visible side by side, so you can see the tax effect of each choice before you commit to it.
You start by entering one trip per line, written as date, trip, miles, for example 2026-01-05, Client visit, 42, plus a rate per mile. Use real numbers from your own business where you can, not round guesses. If you are unsure about a rate, use your best careful estimate and then test a slightly higher rate as well. That second test shows you how sensitive your result is. A plan that only works when every rate is perfect is a fragile plan, and it is better to find that out here than after you have filed a return.
Take this worked example: three trips in January totalling 120 miles at a rate of 0.65 per mile. The tool shows January totals of 120 miles and 78 in mileage value, with each trip listed under its month. Notice how the answer is not just one number. It breaks the result into its parts, so you can see where the money goes at each step. That breakdown is the useful part, because it tells you which part to change if the final number is too high or too low for your business.
The result matters because a mileage claim without a dated log is hard to defend, while a month-by-month log is easy to check. Many small businesses look only at the headline amount and forget the tax hidden inside it. A sale can look profitable and still disappoint after tax, or a cost can look small and still matter once the deductible part is separated. Reading the full result, not just the headline number, is what turns a tax figure into a business decision rather than a hope.
A common mistake is estimating miles from memory at year end instead of recording trips as they happen. It is easy to make because the mistake feels like good business at the time. A lower price feels generous to customers, a claimed cost feels like money saved, and a rough estimate feels close enough. All three can be true and still damage your tax position if the numbers underneath do not support them. The tool helps you catch that problem before you file, while it is still cheap to fix.
Paste each trip the same week you drive it, so the log stays complete and the monthly totals stay honest. This is a practical habit, not a theory. Test the numbers you want, then test a slightly higher rate and a slightly lower rate. Compare the result in each case and ask yourself which result you could live with if the real rate turns out different. The safest plan is often not the most optimistic one. It is the plan that still works when one input moves against you.
There are limits to what a simple calculator can do. it does not verify your miles or your rate, so use your odometer readings and your local approved rate. It cannot decide what your local tax rules allow, predict how a tax office will view a claim, or replace proper records. Those questions need your own records, official guidance, and where needed a qualified adviser. What the tool can do is make sure the arithmetic behind your figures is sound, so that if your treatment is right, the numbers are right too. Sound arithmetic is the foundation, and professional advice builds on top of it.
The figures here are estimates for planning only, not professional tax advice. Your real rates, rules, and business terms may differ, and you should check important decisions with your own records or a qualified adviser where needed. Used that way, this free tool is a practical helper for everyday tax work. Enter honest numbers, read the full breakdown, test a few versions, and choose the treatment that stays honest and defensible.
El Registro de Kilometraje para Impuestos