Best CT600 Software UK: Complete Comparison Guide
Every UK limited company must file a CT600 corporation tax return with HMRC. Choosing the right software can save hours of work and help you avoid costly mistakes.
This guide compares the leading CT600 software options, explains what features matter most, and helps you decide which solution fits your business.
Why You Need CT600 Software
Filing a CT600 manually is no longer an option for most companies. HMRC requires electronic submission with data in iXBRL format — a machine-readable standard that can only be generated by specialist software.
From April 2026, HMRC will shut down their own free filing service. After this date, all companies must use commercial software to file their corporation tax returns. This makes choosing the right software more important than ever.
Good CT600 software should:
- Generate HMRC-compliant CT600 forms automatically
- Create iXBRL-tagged tax computations
- Calculate your corporation tax accurately
- Submit directly to HMRC via the Government Gateway
- Provide clear guidance throughout the process
What to Look For in CT600 Software
iXBRL Support
iXBRL (Inline eXtensible Business Reporting Language) is the format HMRC requires for tax computations. Your software must generate compliant iXBRL files — this isn't something you can create manually.
Some software generates computations only, requiring you to source iXBRL accounts separately. Others handle both computations and accounts in one workflow.
Companies House Integration
If you're filing micro-entity or small company accounts, look for software that handles both HMRC and Companies House submissions. Filing both from one system saves time and ensures consistency between your tax return and statutory accounts.
Pricing Model
CT600 software typically uses one of three pricing models:
- Pay-per-filing — Pay only when you submit (ideal for single companies)
- Annual subscription — Unlimited filings for a fixed annual fee (better for accountants)
- Bundled with accounting software — Included with broader accounting packages
Ease of Use
Some software assumes you're an accountant. Others are designed for company directors with no accounting background. Consider who will be using the software and choose accordingly.
UK CT600 Software Compared
Here's how the main options compare:
TinyTax
Best for: Micro-entity companies and first-time filers
TinyTax is designed specifically for UK micro-entities — companies with turnover under £1 million, assets under £500,000, and 10 or fewer employees. It handles both CT600 filing to HMRC and iXBRL accounts to Companies House in one streamlined workflow.
Key features:
- Automatic tax calculations with marginal relief
- iXBRL accounts generation included
- Companies House and HMRC filing from one form
- Prior year data fetch from HMRC
- Guided process for non-accountants
- Support for dormant companies
- Period splitting for accounting periods over 12 months
Best suited for: Company directors filing their own returns, micro-entities wanting a simple all-in-one solution.
TaxCalc
Best for: Accountants with multiple clients
TaxCalc is established professional tax software used by many UK accountants. It offers comprehensive CT600 functionality including all supplementary pages.
Key features:
- Full CT600 form with all supplementary pages
- Facsimile HMRC form view
- Validation checks before submission
- Multi-client management
- Integration with TaxCalc accounts production
Best suited for: Accountants managing multiple company returns, complex tax situations requiring supplementary pages.
Easy Digital Filing
Best for: Small companies wanting pay-per-file
Easy Digital Filing offers HMRC-recognised CT600 software with a pay-as-you-go pricing model. You can prepare your return for free and only pay when ready to submit.
Key features:
- Pay only when you submit
- iXBRL accounts included
- Instant tax calculations
- Direct HMRC and Companies House filing
Best suited for: Small companies wanting to test the software before committing.
FreeAgent
Best for: Companies already using FreeAgent for bookkeeping
FreeAgent is primarily accounting software, but includes CT600 filing for micro-entities. If you already use FreeAgent for day-to-day bookkeeping, the CT600 integration can be convenient.
Key features:
- CT600 generated from your FreeAgent data
- Most boxes pre-filled automatically
- Integrated with full accounting system
Best suited for: Companies already paying for FreeAgent who want everything in one system.
BTCSoftware
Best for: Accountancy practices
BTCSoftware is professional-grade corporation tax software designed for accountants. It offers powerful features but assumes accounting knowledge.
Key features:
- Full CT600 with all supplementary pages
- Automatic iXBRL computations
- Practice management integration
- Batch processing for multiple returns
Best suited for: Established accountancy practices with many corporate clients.
Comparison Table
| Feature | TinyTax | TaxCalc | Easy Digital Filing | FreeAgent | BTCSoftware |
|---|---|---|---|---|---|
| Micro-entity focus | Yes | No | Yes | Yes | No |
| iXBRL accounts included | Yes | Separate | Yes | Yes | Separate |
| Companies House filing | Yes | Via integration | Yes | No | Via integration |
| Pay-per-file option | Yes | No | Yes | No | No |
| Accountant multi-client | Limited | Yes | Limited | No | Yes |
| All CT600 supplementary pages | Core pages | Yes | Core pages | Core pages | Yes |
| Prior year HMRC fetch | Yes | Yes | No | Yes | Yes |
Which CT600 Software Should You Choose?
If you're a company director filing your own return:
Choose software designed for non-accountants. TinyTax and Easy Digital Filing both offer guided processes that don't assume accounting knowledge. If you're a micro-entity, TinyTax handles both HMRC and Companies House in one workflow.
If you're an accountant with multiple clients:
TaxCalc or BTCSoftware offer the professional features you need — multi-client management, all supplementary pages, and batch processing. The subscription model makes sense when filing many returns.
If you already use accounting software:
Check if your existing software includes CT600 filing. FreeAgent users can file directly from their accounts. This avoids re-entering data but may limit flexibility.
If you have a dormant company:
Most software handles dormant company returns, but some make it easier than others. TinyTax has specific dormant company support with a streamlined process.
If you have complex tax situations:
Companies needing research and development relief, group relief, or other supplementary pages should choose TaxCalc or BTCSoftware which support all CT600 supplementary forms.
HMRC Recognition
All CT600 software must be HMRC-recognised to file directly. You can verify any software on HMRC's list of commercial software suppliers.
Every option in this guide appears on the official list and can submit directly to HMRC via the Government Gateway.
The 2026 Deadline
HMRC's free CT600 filing service will close on 31 March 2026. After this date, all companies must use commercial software.
If you've been using HMRC's free service, now is the time to evaluate alternatives. Don't wait until the deadline — familiarise yourself with new software before you're forced to switch under time pressure.
Filing Your CT600 with TinyTax
TinyTax makes CT600 filing straightforward for UK micro-entities:
- Search for your company — Enter your company number to get started
- Enter your figures — Guided forms walk you through each section
- Review calculations — See your tax liability calculated automatically
- Generate documents — CT600, iXBRL accounts, and computations created instantly
- Submit to HMRC and Companies House — File both in one session
Frequently Asked Questions
Can I file a CT600 without software?
No. HMRC requires CT600 returns to be filed electronically with iXBRL-tagged computations. This format can only be generated by specialist software. Paper filing is not accepted.
Is HMRC's free filing service still available?
Yes, until 31 March 2026. After this date, HMRC will shut down their free service and all companies must use commercial software.
What's the difference between CT600 software and accounting software?
Accounting software handles day-to-day bookkeeping — invoices, expenses, bank reconciliation. CT600 software specifically handles the annual corporation tax return. Some products combine both, while others specialise in tax filing only.
Do I need separate software for Companies House?
Not necessarily. Some CT600 software (like TinyTax) includes iXBRL accounts generation and Companies House filing. Others require you to source accounts separately or use additional software.
What if my accounting period is longer than 12 months?
Extended accounting periods must be split into two CT600 returns — one for the first 12 months, one for the remainder. Good CT600 software handles this automatically, calculating the correct profit apportionment for each period.
Can I switch CT600 software mid-year?
Yes. Each CT600 is independent, so you can use different software for different returns. However, some software fetches prior year data from HMRC, making the transition seamless.
Next Steps
Ready to file your CT600? Search for your company on TinyTax to see how simple corporation tax filing can be. The guided process handles calculations, generates compliant documents, and submits directly to HMRC — all in one workflow.