Koinly review: the crypto tax calculator that speaks HMRC

• Koinly imports your trading history from exchanges and wallets, applies HMRC’s crypto rules to it, and produces the capital gains and income figures your self assessment asks for. Everything is free until the moment you download the report.
• Plans are per tax year and priced by transaction count: $49 covers 100 transactions, $99 covers 1,000, $199 covers 3,000. Casual investors fit the cheapest tier; DeFi users burn through transaction counts faster than they expect.
• The catch is universal to tax software: the output is only as good as the imported data, and a messy history takes an evening of reconciling before the numbers deserve trust.

Crypto tax in the UK is genuinely hard to do by hand. HMRC treats crypto as an asset with its own pooling rules, every trade, swap and sale is a taxable event, and the rules reach into staking rewards and airdrops as income. Our crypto tax guide explains what the rules are; Koinly exists to apply them to your actual history without you building the spreadsheet of nightmares. It has become the default recommendation across much of the industry, so this review checks the recommendation rather than repeats it.

Everything below was checked against Koinly’s own pricing and documentation in September 2026. This page is monetised: sign up through the gold link and Koinly pays us a commission, at no extra cost to you. The link goes to the free tier, no card required, and the criticism stays in regardless; the full arrangement is in our affiliate disclosure.

What you get

You connect your accounts, by read-only API sync for the big exchanges, by wallet address for the major chains, or by CSV upload for anything else, and Koinly rebuilds your entire crypto history in one place: over 20,000 currencies recognised, eight-plus years of historical prices, and automatic matching of transfers between your own wallets so moving coins around is not mistaken for selling them. DeFi trades, NFTs, mining, staking, lending and airdrops are all categorised, spam tokens are filtered out, and a running portfolio tracker with a capital-gains preview comes free.

The tax engine is the point, and for UK users it does the specific things HMRC requires: share pooling with the same-day and 30-day rules applied, capital gains in the shape self assessment wants, and income from staking and the rest totalled separately. It generates dedicated UK reports alongside a dozen other countries’ formats, and a comprehensive audit report showing how every figure was reached, which is exactly the paper you want if HMRC ever asks questions.

What it costs

Prices are in dollars and per tax year, and that second part deserves emphasis: a plan buys unlimited report downloads for one tax year, so catching up on three undeclared years means buying three plans. The free tier softens the whole model: you can import everything and see your gains for any year before paying a penny, so you find out whether the numbers are painful before spending anything. Exchanges will often split one order into dozens of fills; Koinly groups these into a single transaction, which makes the limits less tight than they sound.

Does it get UK tax right?

The rules it applies are the right ones, which is not something every international tax tool can say: plenty handle American cost-basis methods and bolt the UK on as an afterthought. Koinly implements the pooling HMRC actually requires, and its UK report maps onto the self assessment boxes. Where it cannot save you is data quality. A missing exchange account, an unlabelled transfer or a dead CSV shows up as phantom gains or impossible balances, and Koinly’s own reconciliation tools, negative-balance warnings and a double-entry ledger per asset, exist precisely because everyone’s first import needs cleaning. Budget an honest evening for it. The report you generate after reconciling is defensible; the one you generate immediately after importing is a draft.

The history you should know

Koinly launched in 2018, has grown into one of the two or three biggest names in crypto tax globally, and has no data breach or security incident on public record. Still, be clear-eyed about what you are doing: handing one company a complete, identified map of your financial life in crypto. The API keys it requests are read-only, so it can see but never move funds, and nothing about the model requires custody. If that concentration of data bothers you on principle, the UK-built alternative Recap encrypts your data so even the company cannot read it; we have no commercial relationship with Recap and have not yet reviewed it, but privacy-first users should know it exists.

Worth knowing alongside: the era of HMRC not noticing is over. UK exchanges have handed over customer lists for years, and from January 2026 international reporting rules mean platforms collect and report user details as standard. The practical takeaway is that the gap tax software fills is no longer optional record-keeping; it is producing numbers you can stand behind when the letter arrives.

Who it’s for, and who it isn’t

Koinly earns its fee for anyone whose history spans more than one platform, touched DeFi at all, or includes staking income, and for anyone who sold at a loss and wants that loss properly registered against future gains rather than forgotten. It is also the right tool for catching up on past years, since it can rebuild history as far back as your accounts go.

It is overkill if you made a few trades on a single exchange and never moved coins: your exchange’s own statement plus our tax guide may be all you need, and the free tier will confirm as much before you pay. It is the wrong pick for privacy absolutists, as above, and nobody should mistake it for advice: it computes what happened, and a complicated year may still deserve an accountant reading the result.

Common questions

Do I need it if I only made losses?

It is arguably most valuable then. Registered losses offset future gains, and unreported ones quietly expire from usefulness. Koinly’s free preview shows the loss; the paid report gives you the figures to record it properly.

Is connecting my exchange account safe?

The API keys Koinly asks for are read-only: they can list your transactions but cannot trade or withdraw. Create keys with exactly those permissions and nothing more, and revoke them at the exchange any time you like. The seed phrase of a hardware wallet never comes into it and nothing should ever ask for one.

Which plan do I actually need?

Import everything free first; Koinly counts your transactions per tax year and tells you. Most casual investors land in the $49 tier, most active ones in the $99 tier, and if the count surprises you, remember every swap and DeFi interaction is a transaction, not just cash-outs.

Will the report satisfy HMRC?

It produces the capital gains and income figures self assessment asks for, calculated under the UK’s pooling rules, plus an audit trail of how. That is what compliance looks like; what no software can promise is that your imported history was complete, which remains, as ever, on you.

Checked against Koinly’s pricing and documentation in September 2026. This review is updated on a schedule and when something material changes. Koinly pays us a commission on sign-ups through the gold link above, which never changes what we write, in line with our affiliate disclosure and editorial policy.