HMRC's free filing service closes 31 March 2026
Your corporation tax return, filed in minutes — not billed in hours.
Boxfile turns your figures into a compliant CT600 and fully tagged iXBRL accounts, then files them straight to HMRC's gateway. Built for UK micro companies that don't need an accountant to file a simple return.
Founding members lock in launch pricing. No spam — one email when we open.
You're on the list — we'll email you when early access opens.
How it works
Three steps. No jargon. No rekeying.
The same journey an accountant follows — compressed into a guided flow that checks every HMRC business rule before anything is submitted.
Enter your figures
Find your company by number, pick your accounting period, and enter your profit & loss and balance sheet. Plain-English labels — we map them to the right boxes and tags for you.
Review the return
See your CT600, tax computation and micro-entity accounts exactly as HMRC will. Marginal relief, financial-year apportionment and rounding are calculated and reconciled to the penny.
File to HMRC
One click submits through the government gateway. You get HMRC's signed receipt immediately — kept in your account as permanent proof of filing.
Free tool
Check your company's filing position.
Search the Companies House register for your company and see your accounts deadlines, your likely corporation tax period, and the details we'd pre-fill for you — then download a summary for your records.
Data from the Companies House public register. Corporation tax period is estimated from your accounting reference date — HMRC may hold a different period if it has changed recently.
Under the bonnet
Compliance engineering, hidden behind a simple form.
Every return is validated against HMRC's own business rules and the current FRC taxonomy before it leaves your screen.
Full CT600 generation
Every mandatory box computed and cross-checked — the arithmetic HMRC's validator enforces, reconciled before you submit.
Marginal relief, done right
Small profits rate, main rate and marginal relief with correct financial-year splitting — penny-perfect against HMRC's checks.
Tagged accounts & computations
FRS 105 micro-entity accounts and dimensional computations tagged to the current FRC and HMRC taxonomies automatically.
Direct HMRC submission
Files through the official government gateway with IRmark integrity sealing — and stores HMRC's signed receipt for your records.
Errors explained in English
If anything fails validation, you get a plain explanation of what to fix — not a cryptic error code.
Companies House filing
File your micro-entity accounts to Companies House from the same figures — one entry, both authorities. Coming after launch.
Pricing
Less than an hour of an accountant's time.
Simple annual pricing per company. Founding members lock in launch rates for life.
£29 / year + VAT · per trading company
- CT600 + iXBRL computation filed to HMRC
- FRS 105 micro-entity accounts included
- Marginal relief and FY splits handled automatically
- HMRC receipts stored permanently
- Email support from a qualified accountant
FAQ
Questions, answered straight.
HMRC's free filing service is closing — what does that mean for me?
HMRC and Companies House are closing their free online accounts and company tax return service on 31 March 2026. From then, companies must file CT600 returns using commercial software. Boxfile is being built specifically as an affordable replacement for micro companies with simple affairs.
Who is Boxfile for?
UK micro-entity limited companies — typically single-director businesses, contractors and freelancer companies preparing FRS 105 accounts. If your company has complex items like R&D claims, group relief or ring-fence trades, you'll be better served by an accountant for now.
Is Boxfile recognised by HMRC?
Recognition is in progress. Our filing engine already passes HMRC's live test service end-to-end — for both the small profits rate and the main rate with marginal relief — and we're working through HMRC's commercial software recognition process before launch. We'll never let you file anything HMRC's own validator hasn't accepted.
Do I still need an accountant?
Boxfile prepares and files a compliant return from the figures you provide — it doesn't give tax advice. Many micro companies with simple affairs file confidently themselves; if your situation is unusual, we'll tell you so rather than let you file something questionable.
When does early access open?
We're onboarding founding members in small groups ahead of the March 2026 deadline. Join the list above and you'll get one email when your access opens — founding members keep launch pricing for life.