Ask any self-employed person how they track their business mileage, and you'll hear one of three answers: a spreadsheet they maintain inconsistently, a dedicated app they tried for three months and forgot about, or a mumbled admission that they mostly reconstruct it from memory in January.

None of these are great. The spreadsheet requires discipline you don't always have. The dedicated app requires you to remember to open it every time you get in the car. And reconstructing mileage from memory? HMRC doesn't love that approach, and neither does your accountant.

Here's what's strange though: if you use a calendar and you're driving to client meetings, you already have the data. It's right there in your calendar events — the locations, the times, the pattern of your working week. You're just not extracting it.

What the HMRC mileage allowance actually means

For anyone self-employed or claiming business mileage as an employee, HMRC allows you to claim a fixed rate per business mile driven. For the 2025/26 tax year, that's:

If you drive 8,000 business miles in a year (quite modest for someone with regular client meetings), that's £3,600 you can claim against your tax bill. At a basic rate of 20% tax, that's £720 back in your pocket from tax relief alone, before you've thought about fuel, insurance, or wear.

The catch is you have to actually record the miles. HMRC expects a contemporaneous mileage log: the date, the destination, the business purpose, and the distance. "I did about 400 miles in February, I think" isn't going to fly under an investigation.

Why most people don't bother

It's not laziness. It's friction. Tracking mileage properly requires doing something extra every single time you drive somewhere for work — logging it in an app, updating a spreadsheet, jotting it in a notebook. That's a habit most people manage to maintain for a few weeks and then quietly abandon.

Studies on habit formation consistently find that any behaviour requiring active effort at the point of execution has a much lower completion rate than behaviours that happen automatically. Mileage tracking, as it's traditionally set up, requires you to remember and act every time you drive. Most people don't.

Apps like Driversnote, TripLog, and MileIQ try to solve this with automatic trip detection via GPS. They work reasonably well, but they require you to classify trips afterwards (business or personal), they drain battery, and they give you another app to manage. They're better than nothing, but they're still another thing in your life.

The data you already have

Here's the thing: if you use Google Calendar or Microsoft Outlook and you include addresses in your meeting invites (most people do, either deliberately or because Zoom links aren't an address), then your calendar already contains most of what HMRC wants.

The date: in the event. The destination: in the location field. The business purpose: the meeting title. The distance: one Google Maps API call away.

The calendar isn't just a scheduling tool. It's an unintentional mileage log that most self-employed people are sitting on without realising it.

How TravelSync turns calendar data into a mileage report

TravelSync's primary job is creating travel time blocks in your calendar so you know when to leave. But as a side effect of doing that job, it records the distance for every journey it calculates.

For every travel block it creates — whether outbound, return, or a direct journey between meetings — it logs the distance in kilometres (converted to miles for your report). By the time you need to do your accounts, you have a complete record of every business journey, automatically, with no extra effort on your part.

The export is a CSV you can download any time, with columns for:

If you drive an electric vehicle, TravelSync applies the Advisory Electric Rate (7p/mile for home charging, with HMRC's 15p public-charging rate a setting away) as a flat rate instead. There's no 10,000-mile threshold for EVs under the current HMRC rules.

Worth noting: TravelSync's mileage export is designed as a practical tool, not a certified HMRC-ready document. You should review it with your accountant and confirm it meets your specific situation. But it's a significantly better starting point than a spreadsheet reconstructed from memory.

The case for automating the boring bits

There's a broader point here beyond mileage specifically. Self-employed people and small business owners spend a disproportionate amount of time on administrative tasks that don't require their actual expertise — scheduling, expense tracking, reporting. Every hour spent on admin is an hour not spent on the work you're actually good at and get paid for.

The tools that make the most difference aren't the sophisticated ones that do complex new things. They're the ones that quietly handle the small repetitive tasks you'd otherwise have to do manually — like recording every business journey, every single time you drive somewhere for work.

Your calendar already knows where you went. It just needs something to listen.

Start tracking mileage automatically

TravelSync connects to your Google or Microsoft calendar, blocks real drive times before and after physical meetings, and logs every journey automatically. At the end of the month — or the tax year — export a clean mileage report with HMRC rates already applied.

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