HMRC Free Filing Replacement: Complete Guide
HMRC's Company Accounts and Tax Online (CATO) — the free service millions of companies have used to file CT600 returns — closes permanently on 31 March 2026. You need a replacement.
The good news: affordable replacements exist that actually improve on HMRC's service.
What You're Replacing
HMRC's CATO Service
HMRC's free service has offered:
- CT600 Corporation Tax return filing
- Basic accounts preparation
- Joint submission to Companies House
- Free access since 2011
Why It's Ending
- Outdated technology that can't support modern requirements
- Economic Crime and Corporate Transparency Act mandates enhanced validation
- Government policy shift away from providing software
- Funding constraints making maintenance unsustainable
Your Replacement Options
Option 1: TinyTax (Affordable Replacement)
TinyTax is the closest like-for-like replacement for HMRC's service. See current pricing →
| Feature | HMRC CATO | TinyTax |
|---|---|---|
| CT600 filing | ✓ | ✓ |
| Accounts generation | Basic | Full iXBRL |
| Companies House filing | ✓ (joint) | ✓ |
| Trial balance import | ✗ | ✓ |
| Error checking | Limited | Real-time |
- Modern, intuitive interface
- Import data from accounting software
- Better error prevention
- Continues beyond March 2026
Option 2: Paid CT600 Software
If you need features beyond basic filing:
TaxCalc (from £100/year)
- Multi-company support
- Advanced tax planning
- Used by accountants
- Professional practice tools
- Full accounts production
- Comprehensive tax suite
- Integrates with Sage accounting
- End-to-end solution
- Additional modules available
Option 3: Use an Accountant
Outsource CT600 filing entirely:
- Pros: Expert handling, tax advice, peace of mind
- Cons: Cost (£200–£800+ per year)
- Best for: Complex affairs, time-poor directors, those wanting professional oversight
Making the Switch
Step 1: Before March 2026
Download your HMRC history:
- Log in to Government Gateway
- Navigate to Corporation Tax
- Download all CT600 returns, computations, and accounts
- Save securely (you'll lose access after closure)
Step 2: Set Up Replacement Software
For TinyTax:
- Visit tinytax.co.uk/register
- Enter your company registration number
- Authorise through Government Gateway
- Import or enter your company details
Step 3: File Your Next Return
Don't wait until the deadline:
- Complete your next CT600 through new software
- Compare the experience
- Resolve any issues while HMRC is still available as backup
Feature Comparison: Replacements vs HMRC
| Feature | HMRC CATO | TinyTax | TaxCalc | IRIS |
|---|---|---|---|---|
| CT600 filing | ✓ | ✓ | ✓ | ✓ |
| iXBRL accounts | Basic | Full | Full | Full |
| Companies House | ✓ | ✓ | ✓ | ✓ |
| Trial balance import | ✗ | ✓ | ✓ | ✓ |
| Multi-company | ✗ | Limited | ✓ | ✓ |
| Tax planning tools | ✗ | ✗ | ✓ | ✓ |
| Available after 2026 | ✗ | ✓ | ✓ | ✓ |
What Changes (and What Doesn't)
What Changes
| Before | After |
|---|---|
| File through HMRC website | File through commercial software |
| HMRC provides interface | Software provider provides interface |
| Limited error checking | Better validation |
| No import options | Trial balance import available |
What Stays the Same
- CT600 form — Same boxes, same rules
- Deadlines — 12 months from period end
- iXBRL requirement — Accounts must be tagged
- Payment methods — Bank transfer, Direct Debit, etc.
- HMRC processing — Returns handled the same way
Frequently Asked Questions
How much does replacement software cost?
TinyTax offers affordable CT600 filing designed for small companies. See current pricing →
Is the replacement as good as HMRC's service?
Better. TinyTax offers trial balance import, real-time validation, and a modern interface that HMRC's ageing system couldn't match.
What about my old filings?
Download them before March 2026. After closure, you cannot access HMRC's records through CATO.
Can I wait until March 2026 to switch?
You could, but it's risky. Switching early lets you learn the software without deadline pressure and ensures your filing isn't delayed.
Do I need to notify HMRC that I'm switching?
No. HMRC doesn't require notification when you change filing software.
What if I'm not tech-savvy?
TinyTax is designed for non-accountants. The guided workflow walks you through each step, and support is available if you get stuck.
Recommended Action Plan
| Timeline | Action |
|---|---|
| Now | Create TinyTax account |
| Next 30 days | Download HMRC filing history |
| Next filing due | File through TinyTax |
| March 2026 | Fully transitioned before deadline |
Summary
- HMRC's free CT600 service closes March 2026
- Affordable replacements like TinyTax are available
- Switch early to avoid last-minute problems
- Download your HMRC history before access is removed
- The replacement can actually be better than HMRC's service
Ready to switch? TinyTax is the affordable replacement for HMRC's CT600 service. Create your account →