CT600 FILING GUIDE
HMRC Corporation Tax filing portal: what it does now and how to file your CT600
Your HMRC online account still helps you manage Corporation Tax. Filing a CT600 is a different task: after HMRC’s free joint filing service closed, you use commercial software or an agent. Here’s where each part of the process belongs.
Creating an account is free. You pay the filing fee per filing.
01 / THE ACCOUNT AND THE RETURN
What the HMRC Corporation Tax portal does today
Sign in to your HMRC Corporation Tax online account with Government Gateway to manage your tax affairs. It remains useful even though HMRC’s free “File your accounts and Company Tax Return” service (CATO) closed on 31 March 2026.
In your HMRC online account
In commercial filing software
- Prepare and submit a CT600 Version 3 return
- Generate supported iXBRL accounts and a tax computation
- Prepare supported supplementary pages, including CT600A or CT600E
You still use your own Government Gateway user ID and password to authorise the HMRC submission through software. See GOV.UK’s Company Tax Returns guidance for current requirements and service scope. For the change in filing routes, read the GOV.UK closure guidance and our guide to HMRC’s free CT600 service closure.
02 / CHOOSE THE RIGHT TOOL
WeFile vs manual filing
Your HMRC account is for managing Corporation Tax, not for preparing a CT600 in a free online form. The former joint service is closed. WeFile brings supported preparation tasks into one guided workflow, with less re-keying when you import figures. Check whether its scope fits your filing before paying.
| Feature | HMRC online account | Former HMRC free service (closed 31 March 2026) | WeFile |
|---|---|---|---|
| CT600 submission | Not available as a free form in the online account. | Available before closure for eligible returns. | CT600 Version 3 for supported returns. |
| Companies House accounts in the same workflow | Separate Companies House services, not the HMRC account. | Joint filing for eligible companies; check GOV.UK for historic scope. | One workflow where eligible; a separate accounts submission. |
| Accounts generated: FRS 105 micro or FRS 102 Section 1A | Not an accounts preparation tool. | Check GOV.UK for historic scope. | Generated for supported account types from the figures entered. |
| iXBRL tagging | Not provided by the online account. | Check GOV.UK for historic scope. | Generated for supported accounts and computations. |
| Automatic Corporation Tax calculation, including Marginal Relief and associated companies | Not a CT600 calculation workflow. | Check GOV.UK for historic scope. | Calculated from your figures and tax adjustments. |
| P&L and balance sheet reconciliation checks | Not a CT600 preparation workflow. | Check GOV.UK for historic scope. | Checks figures entered into the filing wizard. |
| Imports | Not a CT600 trial-balance import tool. | Check GOV.UK for historic scope. | Xero, QuickBooks Online, FreeAgent and CSV trial balance. |
| Supplementary pages | Not available as a free CT600 filing form. | Check GOV.UK for historic scope. | CT600A and CT600E; CT600B–D and CT600F–P are unsupported. |
| Submission status and receipts | Manage your tax account; not this CT600 submission workflow. | Check GOV.UK for historic scope. | Separate HMRC and, where applicable, Companies House results. |
| Price | Free account access; not a CT600 filing form. | Closed; formerly free for eligible companies. | Account creation is free. Confirm the payable price before purchase. |
Historic-service scope is qualified where it cannot be established from this comparison. Check GOV.UK’s closure guidance rather than treating the former service as an available filing option.
03 / FROM DETAILS TO SUBMISSION
Step-by-step: how the WeFile filing wizard works
The wizard asks for the information relevant to your filing. Some steps appear only for particular companies; the numbered sequence below shows the supported routes, not a requirement to complete every step for every return.
Company Details
Review and confirm the company and accounting period. For Companies House companies, available company details can be pulled from Companies House.
Charity – CT600E
Enter the relevant charity or CASC exemption and CT600E information.
Shown for eligible charity and CASC filings, which use a CT600-only route.
Profit & Loss
Enter income and expenses, or import supported bookkeeping figures, then review the results.
Skipped for dormant filings; also skipped for fully exempt charity filings.
Balance Sheet
Enter assets, liabilities and reserves and check that the figures reconcile.
Not part of the charity or CASC CT600-only route.
Account Type
Select the applicable supported presentation: micro FRS 105 or small-company FRS 102 Section 1A.
Skipped for dormant, charity and CASC filings.
Notes
Review and enter additional accounts notes where applicable.
Repayment
Enter repayment details where a Corporation Tax or Income Tax repayment is due.
Loans – CT600A
Enter relevant loans to participators and repayment details for the s455 calculation.
Shown for applicable close-company filings, not dormant, charity or CASC filings.
Tax & Review
Review the final Corporation Tax computation, adjustments and generated filing documents before submission.
Credentials & submit
Provide your Corporation Tax-enrolled Government Gateway credentials and, for eligible accounts filings, the Companies House authentication code. Pay the applicable filing fee and track each submission result.
A dormant filing skips Profit & Loss and Account Type. Eligible charities and CASCs follow a CT600-only route with the CT600E Charity step; their accounts are not submitted to Companies House through WeFile. For submission mechanics and what happens after sending, see our CT600 submission and status guide.
04 / REVIEW BEFORE YOU SEND
Built-in checks that reduce filing errors
WeFile checks relationships between the information you enter and calculates tax from your inputs. These checks help you review a return; they do not verify the underlying records on your behalf.
Figures that reconcile
Profit and loss and balance sheet figures must reconcile before filing.
Tax from your inputs
Corporation Tax is calculated from the figures and adjustments you provide.
Reserves movement
The movement in retained earnings is checked against the accounts figures.
Carried-forward losses
Loss restriction and the deductions allowance are applied where relevant.
Close-company loans
Where CT600A applies, s455 uses the rate in force when each loan was made.
Submission feedback
Preparation checks and HMRC responses or rejection messages are surfaced for review.
Two tracked results
HMRC and eligible Companies House submissions have separate statuses.
No software can guarantee HMRC or Companies House will accept a filing; you remain responsible for the figures you submit.
05 / TWO DESTINATIONS
Can I submit my CT600 and Companies House accounts in one flow?
Yes, where the company and accounts type are eligible. You prepare the figures in one WeFile workflow, but HMRC receives the CT600 package and Companies House receives a separate accounts submission. Review and retain both acknowledgements; success at one destination does not establish acceptance at the other.
HMRC
CT600 Version 3 and the applicable supporting documents.
Companies House
Eligible statutory accounts, submitted and tracked separately.
Charities, CASCs and entities without a Companies House number use WeFile’s CT600-only route: accounts must be filed or retained separately as applicable. If Companies House reports that a company is not registered for electronic filing, contact Companies House directly rather than retrying that accounts submission.
06 / KEEP THE DATES SEPARATE
Deadlines and penalties
The tax payment, CT600 return and Companies House accounts are separate obligations. These are usual deadlines; your circumstances can change the date that applies.
| Obligation | Usual deadline | Destination |
|---|---|---|
| Pay Corporation Tax | Nine months and one day after the tax period ends | HMRC |
| File the CT600 | 12 months after the accounting period ends | HMRC |
| File private-company accounts | Normally nine months after the accounting reference date | Companies House |
For CT600 returns with a filing date on or after 1 April 2026, the fixed HMRC late-filing penalty is £200 when late and a further £200 after more than three months (£400 in total). Following three successive late returns, those amounts rise to £1,000 each (£2,000 in total). Companies House penalties are separate. See our Corporation Tax deadlines and penalties guide for further context.
07 / BEGIN WHEN YOU’RE READY
Get started for free
Create a WeFile account at no charge. Add your company, prepare and review the filing, then pay the per-filing fee before submitting. Your HMRC submission uses your own Government Gateway credentials; eligible Companies House accounts require the company’s authentication code.
Prices shown are WeFile’s own, not a market benchmark. If current pricing is unavailable, a displayed figure may be a fallback; confirm the payable amount before purchase.
New to the return itself? Start with the CT600 guide, then review the online filing walkthrough.
QUESTIONS, ANSWERED
HMRC Corporation Tax portal FAQs
Ready to prepare your CT600?
Create an account for free, review your figures and pay the filing fee when you’re ready to submit.
This guide provides general information, not accounting, legal or tax advice. Check the rules for your circumstances and seek professional advice where needed. WeFile is independent of HMRC and Companies House. WeFile appears on HMRC's Corporation Tax commercial software suppliers list; inclusion does not imply endorsement, accreditation or guaranteed acceptance.