Corporation Tax filing for UK SMEs, directors, and accountancy practices — validated against HMRC live test ETS byte-for-byte using the HMRC GovTalk CT v1.994 protocol. AI-assisted from trial balance to HMRC acknowledgement — accurate, transparent, and audit-ready.
Free direct-HMRC CT600 submission on Standard until 30 September 2026 — from October £99/year. Cancel anytime before then.
Open source (AGPL-3.0). Your data stays yours. You can see exactly what we file with HMRC.
From trial balance import to HMRC submission — one platform, powered by AI.
Describe your business in plain English. AI prepares your CT600, iXBRL accounts, and tax computation.
Import your trial balance from Sage, Xero, QuickBooks, or CSV. Auto-classify accounts.
Submit directly to HMRC with one click. Real-time status tracking and acknowledgement.
FRS 105 and FRS 102 Section 1A statutory accounts with iXBRL tagging.
Every tax rule is transparent and auditable. AGPL-3.0 licensed.
White-label API for accounting firms. Embed CT600 filing in your own software.
Free for CT600 preparation. From £99/year for direct HMRC filing.
Free
Community-tier users help shape the product — share TB import edge cases, report bugs, contribute on GitHub. No paid support, but the community has your back.
£9/mo
£99 billed annually
£29/mo
£299 billed annually
£99/mo
£999 billed annually
Custom
The Community tier covers CT600 preparation for one company: the wizard, ledger classification, iXBRL accounts (FRS 102 §1A or FRS 105), iXBRL CT computations, and on-screen validation against the HMRC schema. You can file the resulting XML manually via the HMRC Government Gateway. Support is via the community forum and GitHub issues — no 1:1 SLA. Free forever, no credit card.
No. Direct filing through the HMRC Transaction Engine is a paid feature, starting at the Standard tier (£9/month, £99 billed annually). On the Community tier you prepare the CT600 XML in OpenCT and submit it manually via the HMRC Government Gateway.
Professional (£29/month, £299 billed annually) covers up to 5 companies and is built for director groups and sole-practitioner accountants. Practice (£99/month, £999 billed annually) is up to 20 companies with multi-user team access and a Slack support channel — built for accountancy practices managing 10+ clients. At 20 clients, Practice works out at roughly £50 per client per year on annual billing. For more than 20 companies, Enterprise gives you unlimited capacity with SSO and a dedicated account manager.
Community → forum + GitHub issues, community-driven. Standard → email support with a 3 business-day SLA. Professional → priority email with a 1 business-day SLA. Practice → priority email plus a dedicated Slack channel. Enterprise → custom SLA + dedicated account manager.
Yes, at any time. Upgrades take effect immediately and we pro-rate the difference. Downgrades take effect at the end of your current billing period. Your data stays with you across upgrades and downgrades — only feature access changes.
Your data is preserved. If you downgrade from Practice to Standard, for example, only your most recently active company stays editable; the others become read-only until you upgrade again or export them. We never delete customer data on a downgrade — only on an explicit account-deletion request, with a 30-day grace period.
Yes. Practice is £99/month on monthly billing, or £999 billed annually (≈£83/month, ~2 months free). Standard and Professional follow the same pattern — see each tier's "billed annually" sub-label. Enterprise customers receive custom annual pricing based on volume and contract length.
Built on open source. Powered by AI. Designed for accountants.
Three steps from trial balance to HMRC submission.
Upload from Sage, Xero, QuickBooks, or enter manually. AI auto-classifies your accounts.
AI calculates your Corporation Tax automatically. Capital allowances, losses, marginal relief — all handled.
Submit directly to HMRC with one click. CT600, iXBRL accounts, and tax computation — all generated automatically.