Your CT600 was accepted: what should you do next?

In short: HMRC's acknowledgment confirms it received your Company Tax Return, not that it agrees with the figures: HMRC can still correct errors or enquire into the return (GOV.UK: Company Tax Return obligations). Save the acknowledgment with the exact filed pack, then pay the Corporation Tax separately, usually due 9 months and 1 day after the accounting period ends unless the company pays in instalments (GOV.UK: Pay your Corporation Tax bill). Check the Companies House accounts and confirmation statement too, and keep the records for at least 6 years.

HMRC's power to correct or enquire is not a reason to distrust every successful submission. It is a reason to record exactly what the success message proves.

What does HMRC's acceptance actually confirm?

HMRC's acknowledgment confirms receipt of a return, so check that its company, accounting period and submission reference match the final version you intended to file. If there were multiple attempts, make sure the receipt belongs to the final intended version rather than an earlier draft or a different period.

A useful completion note says: "Return for this company and these dates received, reference saved." It should not say "HMRC approved the accounts" unless you have separate evidence supporting that very different claim.

What should you do after your CT600 is accepted, step by step?

Match the acknowledgment to the return you meant to file, save the filed pack, check the tax payment separately, check the company's other filings, record next year's opening position, then confirm the pack is complete. Filing does not pay the tax, which most companies owe nine months and one day after the period ends.

Step 1: Match the acknowledgment to the return you filed

Check that the acknowledgment's company, accounting period and submission reference match the final version you intended to file. If there were multiple attempts, make sure the receipt belongs to the final intended version rather than an earlier draft or a different period. If the software still shows a pending status or the receipt cannot be matched, ask the provider to investigate. Avoid treating a card-payment confirmation as the HMRC acknowledgment.

Step 2: Save the filed pack

Save the exact versions you submitted as one filing pack: the CT600 and applicable supplementary pages, the accounts and tax computation submitted with the return, the submission acknowledgment and reference, your review notes and approval record, and the supporting schedules for adjustments and claims. Use a folder name containing the company and accounting-period end. Distinguish the filed pack from working files, but retain the workings too.

Step 3: Check the Corporation Tax payment separately

Filing the return does not pay the Corporation Tax bill. Check the payment amount, due date and appropriate accounting-period reference through the relevant HMRC service. The ordinary payment rule for companies outside the instalment regime is nine months and one day after the accounting period ends. Leave "tax payment not confirmed" open until it is, and where a payment cannot be matched to the expected period, investigate the allocation with HMRC rather than paying again.

Step 4: Check the company's other filings

Companies House accounts and the confirmation statement are separate from the CT600, so check each one's status; your tax-return receipt does not establish it. For a company with a long first period, check whether another CT600 remains outstanding. For a return prepared by an accountant, make sure both parties agree who handles payment and any remaining filings.

Step 5: Record next year's opening position

Record next year's opening balances and any continuing schedules, such as fixed assets or losses, while the current return is still familiar. Company records generally need to be kept for six years from the end of the last company financial year they relate to, so keep a secure, accessible copy of the pack rather than relying solely on continued access to a particular software subscription.

Step 6: Confirm the filing pack is complete and readable

Open each download once to check that it is readable and belongs to the correct company. Then write a completion note that says exactly what the acknowledgment proves: "Return for this company and these dates received, reference saved." You are done when every file in the pack opens, the note is saved with it, and the payment and other-filing items each show a confirmed status or an open action.

How long should you keep company tax records?

Company records generally need to be kept for six years from the end of the last company financial year they relate to, with situations requiring longer retention. GOV.UK: Running a limited company: company and accounting records explains the retention rules. Keep a secure, accessible copy rather than relying solely on continued access to a particular software subscription.

If you're weighing up how to file next year's return, take the 30-second check to see whether Taxley fits your company.

Next step: use our Corporation Tax deadlines guide to keep filing and payment visible as separate tasks.

Frequently asked questions

Does filing the CT600 pay the Corporation Tax?

No. Filing the return does not pay the bill. Check the amount, due date and accounting-period reference through the relevant HMRC service, and use HMRC's payment guidance and the instalment rules where they apply.

Which documents should you save after filing?

The exact versions you submitted: the CT600 and supplementary pages, accounts and tax computation, HMRC's acknowledgment and reference, review notes and supporting schedules. This is a suggested archive structure, not a statutory document list.

What else does the company still need to file?

Companies House accounts and the confirmation statement are separate from the CT600, so check each one's status. A company with a long first period may also have another CT600 outstanding.

Does acceptance mean an accountant reviewed my return?

No. A submission result says nothing by itself about whether the figures were reviewed, and HMRC's acknowledgment confirms only that the return was received — not that HMRC agrees with the figures. Keep your own review notes with the filed pack.

What if I notice a mistake afterwards?

Preserve the filed version and investigate promptly; do not silently edit your only copy of the evidence. You can usually amend a Company Tax Return within 12 months of its filing deadline (GOV.UK: Company Tax Returns: making changes) — see how to correct a CT600 after filing.

General information, not personalised tax or accounting advice.