Use this page when you already know the filing destination is HMRC and want to understand exactly what gets checked, assembled, submitted and returned to you.
To file a CT600 with iXBRL accounts, we confirm your approved accounts, align the tax computation and CT600 figures, assemble the iXBRL-tagged accounts and supporting attachments, submit the package through the HMRC online route, then return acknowledgement and filing evidence for your records.
You review and approve the iXBRL accounts before we move to filing.
We confirm accounting period, tax references, tax liability and return context.
The iXBRL accounts, CT600 and computation are assembled for submission.
The filing is submitted through the appropriate HMRC online filing route.
We monitor for HMRC acknowledgement, acceptance or rejection response.
You receive filing evidence and references for your records.
| Requirement | Normal deadline | Notes |
|---|---|---|
| Company Tax Return | 12 months after accounting period end | Late filing penalties can apply if the return is missed. |
| Corporation Tax payment | Usually 9 months and 1 day after accounting period end | Applies to taxable profits up to GBP 1.5m. Larger companies may pay by instalments. |
| Accounts and computation | Before final CT600 submission | Final figures should agree across accounts, computation and return. |
| Common issue | Risk | How we prevent it |
|---|---|---|
| Incorrect accounting period | Return rejected or queried | Period dates checked before submission |
| Accounts and CT600 mismatch | HMRC validation or review issue | Computation and accounts cross-check |
| Invalid iXBRL attachment | Technical rejection | Schema, taxonomy and file checks before filing |
| Missing supplementary data | Incomplete return | Applicability review before the final package is assembled |
If HMRC rejects a filing due to our tagging or filing error, we correct it and re-file without additional service charge under the zero-risk guarantee. Security controls include AES-256 encryption, UK-only processing and ISO 27001-aligned handling.
If HMRC rejects a filing due to our tagging or filing error, we correct it and re-file without additional service charge under the zero-risk guarantee. Security controls include AES-256 encryption, UK-only processing and ISO 27001-aligned handling.
Yes, where the required authorisation and filing information are in place. We confirm the filing route before submission.
We will confirm the correct route for your case. Some filings need agent authorisation or client-provided HMRC access before submission.
You receive acknowledgement or acceptance evidence after submission, including references available from the filing response.
Corporation Tax accounting periods can create additional filing periods. We check the period structure before preparing the return.
GOV.UK states the Company Tax Return deadline is 12 months after the end of the accounting period it covers.
For taxable profits up to GBP 1.5m, GOV.UK states the payment deadline is 9 months and 1 day after the accounting period. Larger companies may pay by instalments.
No. We can start preparation, but final filing needs confirmed computation and CT600 figures.
We review the rejection notice, identify the cause, correct any issue within our scope and re-file under the agreed guarantee terms.
Fixed pricing. Expert support. Fast delivery.
We deliver three solutions: iXBRL filing, UKSEF compliance, and ESG reporting. Ready for 2027 mandatory software filing. Our team responds to your questions within 30 minutes during business hours (Mon–Fri, 09:00–17:30).
40–60% lower cost. 30-minute support response. 48-hour delivery.
