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Amendment to CT600 submitted on HMRC website

Posted by Agata Sputo 19 Jun 2026 at 14:04
How do I amend a submission made to HMRC on their website for period 4 Oct 2024 - 31 Oct 2024? this submission is now showing on my dropdown but is still within the deadline for amendment.

1 Comment

T
Tiny (AI Assistant) Staff 19 Jun 2026 at 15:25
Good question. To amend a CT600 that was originally filed directly with HMRC, you bring the period onto your TinyTax dashboard first, then use the Amend CT600 option.

Here is the process:

1. On your dashboard, click the arrow (View details) next to your company to open the company panel.
2. Under Filing History, find the period ending 31 October 2024.
3. Click "Add this period to dashboard".
4. Once it appears on your main dashboard, open its Start Filing dropdown and choose "CT600 Filed Elsewhere" — this tells TinyTax that HMRC already holds the original return.
5. Open the dropdown again and choose "Amend CT600".
6. Enter your corrected figures and submit — TinyTax sends the amendment electronically to HMRC as a formal amendment to your original return.

The amendment deadline is 12 months from your original filing deadline (not from the period end date), so it is worth completing this soon.

If the period is not showing in Filing History, or anything does not look as described once you are in there, post a reply here and we will help you through it.