Accusolve is an AAT AML-supervised UK accountancy practice supporting startups, SMEs and overseas directors of UK companies. We prepare the Company Tax Return package, explain the calculations and submit agreed filings using suitable software.
The CT600 is one part of the filing package. Depending on your company and accounting period, the return includes:
We review expenses and applicable allowances. Capital allowances, group relief, R&D claims and other specialist reliefs are considered only where relevant, supported by evidence and included in our agreed work. Companies House annual accounts filing remains a separate obligation.
HMRC's former free joint online filing service closed on 31 March 2026. Company Tax Returns now generally require suitable commercial filing software, with limited paper-return circumstances such as filing in Welsh or having a reasonable excuse. We prepare and file returns through appropriate professional software; see HMRC's guidance on the service closure. Our guide to CT600 filing after March 2026 explains the software change and what companies need to prepare.
The return is normally due 12 months after the end of the Corporation Tax accounting period. Payment is normally due 9 months and 1 day after that period for companies outside instalment-payment rules, so payment can fall before the filing deadline. We review the relevant periods and explain your Corporation Tax obligations.
First accounts or accounts covering more than 12 months can require more than one tax return because a Corporation Tax accounting period cannot exceed 12 months. Check the applicable periods rather than assuming one accounts deadline covers every return and payment. See GOV.UK Company Tax Return guidance.
If the company is not trading, we review HMRC's status and any notices before deciding what is required. Our dormant company accounts support explains the separate Companies House and HMRC obligations.
We agree the records and authorisation needed for your circumstances and flag missing information that may affect preparation or submission.
| Task | What it covers |
|---|---|
| Annual accounts | Statutory financial statements and the applicable Companies House accounts filing. The Company Tax Return is a separate submission. |
| Company Tax Return / CT600 | HMRC's return package, including relevant accounts and tax computations. Payment and return deadlines are separate. |
| Dormant accounts | Companies House accounts for an eligible dormant company. HMRC dormancy and any notice to deliver a tax return must be checked separately. |
| Confirmation statement | A check of company information on the register, rather than a set of accounts or a tax return. It remains a separate obligation for dormant companies. |
Send the company details, period, known deadline and any HMRC or Companies House notice with your enquiry. We can identify the relevant filing work and agree each part of the scope.
Tell us your accounting periods, available accounts and records, HMRC notices, previous returns and any relief claims to review. We review the records and deadline before agreeing the work.
Your quote should identify the services and period covered, reporting frequency where relevant, the fee and VAT treatment, and any exclusions or third-party charges. Bookkeeping catch-up, earlier-period corrections and additional advice are agreed separately unless included. Confirm the scope and your responsibilities before instructing us.
Discuss your accounts, HMRC notices and filing deadlines with our UK accountancy and tax team. We can prepare the required return package and explain the next steps.
Professional CT600 Tax Return Support
