Corporation Tax Self Assessment requires a company to calculate its taxable profits and submit the relevant return with accounts and tax computations.
The tax calculation is not always the same as the accounting profit. Adjustments, reliefs and the accounting period need to be considered.
Register and establish the periods
Notify HMRC when the company becomes active for Corporation Tax and check which periods require a return.
Companies House accounts and HMRC returns are distinct obligations. Completing one does not automatically complete the other.
File and pay on time
The return deadline and payment deadline differ. Larger companies may need to pay by instalments, and associated companies can affect the relevant thresholds.
Use the Company Tax Return guidance and our Corporation Tax reference when establishing the timetable.
Filing arrangements also need to be current. The former combined online service should not be assumed to remain available; check HMRC’s filing guidance.
Other returns and corrections
Certain payments, such as qualifying interest payments, can require tax deductions and separate reporting. Check these before paying rather than waiting for the annual company return.
If an error is identified, review the permitted amendment route and deadline. HMRC can also correct or enquire into returns under the applicable rules.
Retain the evidence
Keep accounting records, computations and documents supporting claims and transactions. Clear records help both the original preparation and any later enquiry.
Agree who monitors deadlines, authorises payment and supplies information about unusual transactions.