CT600 Filing After March 2026: Your Options Explained
From 1 April 2026, HMRC's free CT600 filing service will no longer exist. But filing Corporation Tax returns remains mandatory. This guide explains exactly what changes and what your options are.
What Changes on 1 April 2026
Before: HMRC's Free Service
Until 31 March 2026, you could file your CT600 through:
- HMRC's Company Accounts and Tax Online (CATO) service
- Free to use
- Filed CT600 and accounts together
- Forwarded accounts to Companies House automatically
After: Software-Only Filing
From 1 April 2026:
- HMRC's free service is gone — permanently closed
- You must use commercial software to file CT600 returns
- Filing obligations remain unchanged — same deadlines, same requirements
- Software can be free or paid — options exist at various price points
Your CT600 Filing Options After March 2026
Option 1: Free CT600 Software
Yes, free options exist. You don't have to pay to file your CT600.
TinyTax offers completely free CT600 filing for micro-entity companies:
- Prepare and submit CT600 returns
- Generate iXBRL accounts
- File to both HMRC and Companies House
- No subscription fees
- No hidden costs
Option 2: Paid CT600 Software
If you need advanced features or have complex requirements:
| Software | Typical Cost | Best For |
|---|---|---|
| TaxCalc | £100+/year | Accountants, multiple companies |
| IRIS | £200+/year | Large practices |
| Sage | £150+/year | Sage accounting users |
| BTCSoftware | £100+/year | Professional practices |
Option 3: Use an Accountant
Accountants use professional software to file on your behalf. Costs vary:
- Basic CT600 preparation: £150–£400/year
- Full accounts and tax service: £500–£2,000+/year
- Your affairs are complex
- You want professional advice
- You prefer not to handle it yourself
Option 4: Paper Filing (Limited)
In rare cases, you may be able to file a paper CT600:
- Charities registered with HMRC
- Community amateur sports clubs (CASCs)
- Dormant companies in some circumstances
What Stays the Same
Filing Deadlines
Corporation Tax return deadlines remain unchanged:
- 12 months from your accounting period end date
- Late filing penalties still apply
CT600 Form
The CT600 form itself doesn't change. You're still completing the same return, just through different software.
iXBRL Accounts
Accounts attached to your CT600 must still be in iXBRL format. Good software (including TinyTax) generates this automatically.
Companies House Filing
Your statutory accounts still need filing with Companies House. Many software packages (including TinyTax) handle both in one go.
Payment Methods
How you pay Corporation Tax doesn't change:
- Bank transfer
- Direct Debit
- Corporate debit/credit card
Timeline: What to Do and When
| Date | Action |
|---|---|
| Now | Download your HMRC filing history |
| Before your next filing | Set up account with new software |
| Next filing due | File through new software |
| 31 March 2026 | HMRC service closes |
| 1 April 2026 onwards | Software-only filing |
| 1 April 2027 | Companies House WebFiling also closes |
How to Prepare
Step 1: Download Your HMRC History (Now)
Before the service closes, download:
- All past CT600 returns
- Computations
- Submitted accounts
- Submission receipts
Step 2: Choose Your Software (Now)
Don't wait until the deadline. Evaluate options now:
- What features do you need?
- What's your budget?
- Do you want to file yourself or use an accountant?
Step 3: Set Up and Test (Before March 2026)
Create your account and familiarise yourself with the software:
- Enter company details
- Set up HMRC connection
- Understand the filing process
Step 4: File Your Next Return Through New Software
Practice with a real return before the old service closes. This way:
- You learn the software properly
- You can compare to your old process
- Any issues are resolved with time to spare
Frequently Asked Questions
Will CT600 filing cost me money now?
Not necessarily. Free options like TinyTax exist for micro-entity companies.Can I still file accounts and CT600 together?
Yes. TinyTax and other comprehensive software handle both. The joint filing concept continues, just through commercial software.What if I forget to switch before March 2026?
You'll need to quickly set up software when you need to file. Avoid this stress by switching early.Do I need to tell HMRC I'm switching?
No. HMRC doesn't require notification when you change filing software.What about very old returns? Can I still amend them?
You can amend returns up to 12 months after the filing deadline through commercial software. For older amendments, contact HMRC directly.Is the deadline really final?
Yes. The closure is required by the Economic Crime and Corporate Transparency Act 2023. An extension is not expected.What About Companies House?
Companies House is making separate changes:
- 1 April 2027: WebFiling for accounts closes
- Software-only filing required for all accounts
- No more abridged accounts
- Enhanced disclosure requirements for micro-entities
Summary
After March 2026:
- HMRC's free CT600 service closes permanently
- You must use commercial software
- Free options (like TinyTax) are available
- Filing deadlines and requirements stay the same
- Prepare now to avoid last-minute problems
Start preparing today. TinyTax offers free CT600 filing. Create your account →