Why crypto tax apps charge you every April for maths your laptop can do

If you have used a crypto tax app for more than one tax year, you have noticed the pattern. The import is free. The dashboard is free. The number at the top of the screen, your gain for the year, free. The button that turns that number into a report you can actually file costs money, and it costs money again next April, for the same portfolio, the same history, often the very same transactions you already paid to process.

You probably suspected this was a choice rather than a necessity. You were right, and the vendors’ own pricing pages are the receipts.

A UK investor with 1,000 transactions needs Koinly’s Hodler plan, which is labelled per tax year, so three filed years is three purchases. CoinLedger’s equivalent works the same way, and their FAQ says plainly that each tax report is a one-time purchase, per year. CoinTracking and Recap sell annual subscriptions instead, so your access to your own reports ends when the subscription does. Every one of them paywalls report downloads entirely. None of this is hidden, it is published and linked above, and it all follows from one architectural decision made years ago. The figures move often enough that they are deliberately not quoted here, read them from the vendors’ own pages.

These platforms ingest your transaction history onto their servers and compute there. That has real costs, storage, compute, security, staff, and those costs recur per user per year. A business with per-user recurring costs needs per-user recurring revenue, so per-tax-year pricing is not greed, it is the honest consequence of the architecture. The part that deserves scrutiny is different. The architecture was never necessary.

Capital gains matching is not heavy computation. Same-day matching, the 30-day rule, section 104 pooling, this is date sorting and arithmetic. A ten-year, ten-thousand-transaction history computes in moments on the laptop you already own. The server does not exist because the maths needs it. The maths runs fine in a browser tab, and always did.

Run the engine on the user’s machine instead and the recurring cost per user falls to roughly zero. Then the pricing logic inverts. Reports can be free, because generating one costs the vendor nothing. Past tax years can be included, because recomputing them costs nothing. Nobody needs to charge you again next April, because next April costs nothing either.

There is a second consequence worth more than the money. A tax app that never receives your data cannot leak it, cannot be subpoenaed for it, cannot train on it, and cannot hold your own reports hostage to a lapsed subscription. Your complete financial history, linked to your identity and your wallet addresses, is exactly the kind of dataset that should not sit in a growth-stage company’s database if it does not have to. We wrote about what these apps hold and what that implies separately, without drama, because the plain facts carry the point.

The honest caveats, because being right is not the same as the other side having nothing. Server platforms do get real things from the server, sync jobs that run while you sleep, data that follows you across devices with no file in your hand. Recap deserves its specific credit, they encrypt on your device before upload and describe a zero-knowledge design, meaningfully better than the default even though the data still leaves and the meter still runs. These are genuine trade-offs, and anyone selling you certainty in either direction is selling.

But be precise about what the April charge buys. It does not buy computation, your laptop does that for free. It buys the continued rental of a copy of your own history.

gains.tax is our answer. UK capital gains computed entirely in your browser, every disposal cited to the rule that matched it, free under 1,000 transactions with every report included, one £39 fee above that covering every tax year, past and future. Open the network tab while it runs. Nothing moves.