Updated July 2026
On 31 March 2026 HMRC permanently closed Company Accounts and Tax Online (CATO) — the free online service that thousands of small companies used to file their Company Tax Return (CT600) and accounts. If you own a property company and filed your last return through HMRC's website, that route no longer exists.
From 1 April 2026, every UK limited company must file its CT600 using commercial software. There is no grace period and no replacement government portal. HMRC's stated reason is that the old service no longer meets modern digital standards or the requirements of the Economic Crime and Corporate Transparency Act.
Only the filing mechanism changed. Your obligations are exactly the same as before: your company still owes corporation tax on its rental profit, still pays it 9 months and 1 day after the end of its accounting period, and still files its return within 12 months. The accounts still have to be prepared under the same standards (FRS 105 for most small buy-to-let companies) and submitted in iXBRL format — CATO used to do that tagging for you invisibly; now your software has to do it.
Companies House filing is separate and unaffected for now: you can still file your accounts there directly. (Software-only filing at Companies House is coming in April 2028 — a separate change.)
| Option | Typical cost | Best for |
|---|---|---|
| An accountant | £300–£800+ per year | Companies with anything complicated: property purchases or sales this year, groups, mixed activities, overdrawn director loans. |
| General-purpose filing software | £25–£119 per return | Companies comfortable preparing their own accounts and computation, and filling in the full CT600 themselves. |
| This site | First filing free, then £19/year | Simple buy-to-let companies only: residential lets, micro-entity, no disposals, profitable year. We prepare the FRS 105 accounts, the tax computation and the CT600 from plain-English questions. |
We are deliberately narrow. If your company doesn't fit our guarded scope — say it sold a property this year — the wizard tells you immediately, explains why, and you've lost nothing. We would rather send you to an accountant than guess at your tax.
Check your records. Access to returns filed through CATO ended when the service closed, so make sure you have copies of your last filed accounts and computation. If you don't, your accountant (if you had one) or HMRC can help — call the Corporation Tax helpline with your UTR.
Note your deadlines. Find your accounting period end date on a Companies House search of your company. Corporation tax is due 9 months and 1 day after that date; the return is due 12 months after. Late filing penalties start at £100 and escalate.
Choose your route. If your company is a straightforward buy-to-let SPV, try our 60-second eligibility check — no signup, and it tells you honestly if you don't fit. You can also estimate your bill first with the buy-to-let company tax calculator, and keep your books tidy for next year with our free SPV bookkeeping spreadsheet.
Answer plain-English questions; we prepare iXBRL accounts, the computation and the CT600. If your company doesn't fit, we say so immediately.
Start the free eligibility check