The simplest way for UK micro-entities to submit Corporation Tax returns and iXBRL accounts directly to HMRC. No accountant needed.
HMRC
Recognised
iXBRL
Compliant
~5 min
Avg filing time
UK
Based & supported
HMRC closed its free filing service on 31 March 2026. SmallTax is here to fill the gap — at a fraction of the cost of an accountant.
Simple process
Add your company details and enter your income, expenses, and balance sheet. SmallTax guides you field by field.
We calculate your Corporation Tax liability, apply marginal relief, and generate your iXBRL accounts. You review everything before submitting.
One click sends your CT600 and accounts directly to HMRC over the Government Gateway. Confirmation comes back in minutes.
Everything included
Full Corporation Tax return including the CT600A supplement for close companies with loans to participators (s.455 CTA 2010).
Built-in charity supplement for registered charities, CASCs, and other exempt bodies — covers gift aid income, exempt income, and non-qualifying expenditure.
Inline XBRL-tagged micro-entity accounts covering the full P&L and balance sheet, ready for HMRC and Companies House.
Connect directly to Xero or QuickBooks Online and pull your trial balance with one click — no CSV exports, no manual uploads. Accounts are mapped to CT600 fields automatically.
Upload your trial balance from any accounting software (Xero, QuickBooks, Sage) as CSV or Excel. AI automatically maps accounts to CT600 fields — review and apply in one click.
Marginal relief, s.455 tax, corporation tax liability, and all CT600 boxes calculated automatically from your figures.
Accounting periods over 12 months are automatically split into two CT600 returns per HMRC rules — SmallTax creates both periods and tracks their deadlines separately.
Files straight to HMRC via the Government Gateway API. No posting, no third-party agents, no delays.
Multi-client view for accountants and bookkeepers: unified client list with urgency sorting, deadline tracking, and status filters — see every client's CT600 and accounts deadline at a glance.
Accountants can queue and submit CT600 returns for multiple clients in one workflow — no switching accounts, no re-entering credentials. Ideal for practices filing for unlimited companies at year-end.
SmallTax generates fully-tagged iXBRL FRS 105 accounts ready for Companies House. Direct software filing via the CH digital API will be available when the service opens (expected 2027–2028).
Making Tax Digital VAT returns submitted directly to HMRC — coming soon. Link your accounting software, review your VAT figures, and file your VAT 100 return without leaving SmallTax.
End-to-end encryption, row-level database security, and enterprise-grade EU-hosted infrastructure. Your data never leaves UK/EU servers.
Security & data residency
SmallTax is built on enterprise infrastructure. Your data is encrypted, access-controlled, and never leaves UK/EU servers.
All data is stored on servers in Ireland (EU West). Your accounts never leave the UK/EU jurisdiction — fully aligned with UK GDPR.
TLS 1.3 encrypts all data in transit. AES-256 encrypts all data at rest. Your financial figures are never stored or transmitted in plain text.
Database access is enforced at the row level. It is architecturally impossible for one user to read another company's data — even if credentials were compromised.
Passwords are hashed with bcrypt and never stored in plain text. Two-factor authentication is available to protect your account.
Your financial data is yours. We do not sell, rent, or share it with advertisers or third parties. Read our Privacy Policy for the full picture.
Data processing agreements, right to erasure, data portability, and a full privacy policy. Compliant with the UK GDPR and Data Protection Act 2018.
Transparent pricing
All prices exclude VAT. No per-submission fees. No surprises.
Always free to prepare your return — you only pay when you submit.
For companies with no trading activity
For active trading companies
For directors with several companies
Only filing once this year? — no subscription required.
Built for UK small business
£300+
Typical accountant fee for a CT600
SmallTax costs a fraction of that — and you stay in control of your own filing.
~5 min
Average time to complete a return
Step-by-step guidance, auto-calculations, and direct HMRC submission mean no back-and-forth.
31 Mar 2026
HMRC free filing service closure
HMRC closed its own free tool in March 2026. SmallTax fills the gap — at a fraction of the cost of an accountant.
FAQ
Join hundreds of UK company directors who file with SmallTax. Create your account in seconds — no credit card required.