File your CT600 online.
Ready to submit your Corporation Tax return? Follow our practical, step-by-step guide to filing online to ensure rapid HMRC acceptance and avoid penalties.
What you need before you start
Gathering these details beforehand ensures a smooth, uninterrupted online filing experience.
Company UTR
Your 10-digit Unique Taxpayer Reference, found on correspondence from HMRC.
Government Gateway
Your User ID and Password, fully enrolled for Corporation Tax services.
Companies House Auth Code
The 6-alphanumeric code for your company if you are filing accounts simultaneously.
Accounting Period Dates
Confirm your start and end dates. They typically span exactly 12 months.
Trial Balance
Finalized bookkeeping figures to input your Profit & Loss and Balance Sheet accurately.
The WeFile wizard
Our guided workflow drastically simplifies the traditional tax return format.
Select Company & Period
We pull your expected accounting periods directly from the Companies House API to ensure dates align perfectly.
Enter Profit & Loss
Input your revenue, costs, and expenses. We'll automatically identify your net trading profit.
Balance Sheet & Capital Allowances
Detail your assets and liabilities, and apply capital allowances directly to the correct asset pools.
Review Computed Tax
Review our automated tax computation which seamlessly handles marginal relief calculations.
Provide Credentials
Securely input your Gateway ID and authentication codes just before submission.
Pay & Submit
Complete the transaction to instantly dispatch the return to HMRC and Companies House simultaneously.
Key deadlines
Corporation Tax Payment: Due 9 months and 1 day after the end of your accounting period.
Companies House Accounts: Must be filed exactly 9 months after your accounting reference date (or 21 months from incorporation for your first accounts).
CT600 Return: The official tax return is due 12 months after the accounting period end.
What happens after you submit
Upon submission, you instantly receive an official IRmark receipt confirming transmission.
WeFile continuously polls HMRC and Companies House for acceptance updates. Once verified, you can download your official CT600 and generated iXBRL Accounts directly from your dashboard in secure PDF format.
Common reasons a CT600 is rejected
Avoid these common pitfalls to guarantee rapid HMRC acceptance.
UTR / Company Number Mismatch
HMRC cross-references your Company Registration Number with the UTR you provide. If they don't match exactly, the submission will bounce immediately.
Missing Original Return
If you try to submit a return marked as an 'amendment' but HMRC has no record of an original return for that exact period, it will be rejected.
Authentication Failures
Providing incorrect Government Gateway credentials, or using an account that isn't yet enrolled for Corporation Tax specifically, will prevent the filing.
Unrecognised Periods
HMRC expects specific accounting periods based on what Companies House reports. Check your online HMRC dashboard if your dates are being rejected.