Best CT600 Software for 2026: Complete Comparison
With HMRC's free CT600 filing service closing in March 2026, choosing the right software is more important than ever. This guide compares the best options for different needs and budgets.
Quick Comparison
| Software | Best For | Price | Free Option |
|---|---|---|---|
| TinyTax | Small companies, DIY filing | Free | ✓ Yes |
| TaxCalc | Accountants, multiple companies | £100+/yr | ✗ No |
| IRIS | Large practices | £200+/yr | ✗ No |
| Sage | Sage accounting users | £150+/yr | ✗ No |
| BTCSoftware | Professional firms | £100+/yr | ✗ No |
Our Top Pick: TinyTax
Best for: Small and micro-entity companies who want free, reliable CT600 filing.
Why TinyTax Wins
Genuinely free — No trial periods, no "upgrade to submit", no hidden fees. TinyTax is free for micro-entity companies, period.
Purpose-built for small companies — Not a stripped-down accountant tool. TinyTax is designed for company directors filing their own returns.
Complete solution — CT600 + iXBRL accounts + Companies House filing in one place.
TinyTax Features
| Feature | Included |
|---|---|
| CT600 return preparation | ✓ |
| Electronic HMRC submission | ✓ |
| iXBRL accounts generation | ✓ |
| Companies House filing | ✓ |
| Trial balance import | ✓ |
| Corporation tax calculation | ✓ |
| Error validation | ✓ |
| Multi-year support | ✓ |
TinyTax Limitations
- Best suited for micro-entities and simple small companies
- Limited practice management features
- Not designed for accountants managing many clients
Detailed Reviews
TaxCalc
Best for: Accountants and firms managing multiple clients.
Price: From £100/year (varies by package)
Strengths:
- Comprehensive tax return coverage (personal, partnership, company)
- Strong multi-company support
- Practice management tools
- Established reputation
- No free tier
- More complex than needed for simple filings
- Learning curve for new users
IRIS
Best for: Large accountancy practices needing full practice suite.
Price: From £200/year
Strengths:
- Professional-grade software
- Complete practice management
- Training and support
- Integration with IRIS accounts
- High cost for small practices
- Complex implementation
- Subscription required
Sage
Best for: Companies already using Sage accounting software.
Price: From £150/year
Strengths:
- Seamless Sage integration
- End-to-end accounting solution
- Strong UK support
- Best value if already using Sage
- Limited standalone appeal
- Subscription model
BTCSoftware
Best for: Professional firms wanting dedicated filing software.
Price: From £100/year
Strengths:
- Focused CT600 and accounts software
- Professional features
- Used by many practices
- No free option
- Primarily targets accountants
- Less intuitive for DIY users
Feature Comparison Table
| Feature | TinyTax | TaxCalc | IRIS | Sage | BTC |
|---|---|---|---|---|---|
| Price | FREE | £100+ | £200+ | £150+ | £100+ |
| CT600 filing | ✓ | ✓ | ✓ | ✓ | ✓ |
| iXBRL accounts | ✓ | ✓ | ✓ | ✓ | ✓ |
| Companies House | ✓ | ✓ | ✓ | ✓ | ✓ |
| Trial balance import | ✓ | ✓ | ✓ | ✓ | ✓ |
| Tax calculation | ✓ | ✓ | ✓ | ✓ | ✓ |
| Error checking | ✓ | ✓ | ✓ | ✓ | ✓ |
| Multi-company | Limited | ✓ | ✓ | ✓ | ✓ |
| Practice management | ✗ | ✓ | ✓ | ✓ | ✓ |
| Personal tax | ✗ | ✓ | ✓ | ✓ | ✓ |
| Free tier | ✓ | ✗ | ✗ | ✗ | ✗ |
Choosing the Right Software
Choose TinyTax If:
- You're a micro-entity or small company
- You want free CT600 filing
- You prefer a simple, guided interface
- You're comfortable filing yourself
- Budget is a primary concern
Choose TaxCalc If:
- You're an accountant managing clients
- You need multi-company support
- You want comprehensive tax coverage
- You're willing to pay for advanced features
Choose IRIS If:
- You run a larger accountancy practice
- You need full practice management
- You want professional support and training
- You're already in the IRIS ecosystem
Choose Sage If:
- You already use Sage accounting
- You want end-to-end integration
- You prefer one provider for everything
Choose BTCSoftware If:
- You're a professional firm
- You want dedicated filing software
- You need professional-grade features
What About HMRC's Free Service?
HMRC's Company Accounts and Tax Online (CATO) closes on 31 March 2026. It won't be an option after this date.
If you've been using HMRC's service, TinyTax is the closest like-for-like free replacement.
Frequently Asked Questions
Which software is best for a first-time filer?
TinyTax — it's free and designed for non-accountants with a guided workflow.Do I need to pay for CT600 software?
No. TinyTax offers free CT600 filing for micro-entity companies.Can I switch software later?
Yes. Your HMRC and Companies House accounts stay the same regardless of which software you use.What if I need an accountant's help?
Any of these software options can be used by accountants on your behalf. Ask your accountant what they recommend.Is free software as reliable as paid?
TinyTax uses the same HMRC submission channels as paid software. The reliability is equivalent.Summary
For most small companies:
- TinyTax offers everything you need for free
- No reason to pay unless you need accountant-level features
- Switch from HMRC's service early to be ready for 2026
- TaxCalc or IRIS offer comprehensive practice tools
- Worth the investment for professional features
- Consider multi-year licenses for value
TinyTax is the best free CT600 software for small companies. Create your account →