Back to Community
1

RE-FILING AMENDED CT600- REJECTED BY HMRC

Dear Tim Fouracre, Tiny Tax

Good afternoon. Thankyou for fixing the glitch that stopped me correcting and saving my Corporation Tax rebate and correcting the Profit and Loss account. It is now doing what I need it to do and saving the amended Corporation Tax Return.

I now have a rejection from HMRC in the process of filing. Was there somewhere the CT600 was not marked as an Amendment, because I put in the correct credentials. I am sure it had been marked as an Amendment return in which case it should have been accepted, as this is showing for the CT600 I am correcting.

The message I received from HMRC regarding an Unsuccessful Submission was "Unfortunately it could not be accepted as it failed HM Revenue and Customs (HMRC) online data checks". What could these failed data checks be if not to do with the UTR, my Agent login credentials or nothing to do with the file being marked Amended (I am sure this was so)? You will see from your record that I tried to submit the Amended CT600 but it failed.

There was no issue filing the CT600 through your platform first time around, so what is it about the re-submission that HMRC do not like?

I have had a week trying to correct one small error in the CT600 for my client, so if I can get this through to full submission I would be most grateful.

Many thanks your all your assistance and excellent customer service. I must be one of your most well-known customers by now as you have worked through issues in correcting a previously submitted CT600 through to the final submission stage.

Kind regards

Ian Pennell
(Cumbria)

1 Comment

T
Tim Fouracre Staff 27 Jan 2026 at 09:20
Thanks for your patience — we've found the root cause. When you used the dashboard "Amend CT600" option, the new session wasn't being linked to your original CT600 in our database. That caused our system to block the submission before it ever reached HMRC (so the error you saw wasn't actually from HMRC).

We've now fixed this, and your amendment is ready to submit.

To submit your amended CT600, please use this link:

https://tinytax.co.uk/submission-form.php?prefill=FS_20260123125551_234662b4

Your previous work should still be there. Review the figures and submit when ready.

If anything looks odd or you hit another error, just reply here and we'll jump on it straight away.