Preparing and filing a CT600
A CT600 in A4O Accounts starts from your posted books. The return builds its own accounts and tax computation for the period, and you check each step before anything goes to HMRC. Changes you make there apply to the return only. Your books are never changed.
Before you start
- The company needs a Registration Number and a 10-digit UTR. See setting up your HMRC details.
- Your bookkeeping for the period should be posted. Only posted entries count.
- An accounting period can’t be longer than 12 months.
1. Create the return
- Go to Accounts & filing → CT600 returns and click New Submission.
- Enter the Period Start and Period End.
- Under Prepare this return’s accounts as, choose micro-entity (FRS 105), small company (FRS 102) or full accounts.
- Fill in Approved by the Board, Signed by and both Average employees fields. A live filing needs the approval date.
- Tick any Supplementary Pages you need, such as CT600A for loans to directors or shareholders, then click Save Draft.
2. Check each section
Open the return and work down its sections:
- Accounts, Detailed P&L and Notes: the accounts HMRC will receive, editable for this return.
- Tax computation: profit to taxable profit, with add-backs and capital allowances. Use Edit adjustments to change them and Recalculate to update. Add CT600A or CT600L pages here if you need them.
- CT600 return: every box, filled in from the above. Click Continue to submission when it looks right.
- Submission: previews of the accounts and computation in iXBRL, and the full XML HMRC will receive.
3. Submit
- Click Submit to HMRC. The dialog checks the return first. If the documents are out of date, a figure fails a check, or the size rules refuse the accounts, it says so and asks you to fix it or give a reason.
- Send a test first: leave Test Mode ticked. Nothing is filed. Afterwards, Reopen as draft puts the return back into draft.
- To file for real, untick Test Mode, enter your Government Gateway Sender ID and Password, and submit. A live return can’t be changed once it’s submitted.
4. Check the result
The return shows Pending while HMRC processes it, then Accepted or Rejected. Use Check Status to ask HMRC again. Each attempt is listed under Submission history. If a return is rejected, reopen it as a draft, fix the problem and submit again.
Paying the tax is separate. Filing the return doesn’t pay HMRC.