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tax return submission

Posted by Dayo Ogunseye 10 Nov 2025 at 16:22
I'm unable to submit the tax return despite entering the correct details. I keep getting a message to 'submit in right format'

3 Comments

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Tim Fouracre Staff 10 Nov 2025 at 16:38
Hi Dayo,

That error usually comes down to one of these:

Companies House Authentication Code
- Exactly 6 alphanumeric characters (e.g., AB123C)
- Find it in your Companies House account or incorporation documents

Company UTR
- Exactly 10 digits (no spaces or dashes)
- Use the Corporation Tax UTR (not a personal UTR)

Dates
- Check that all dates are entered in the required format

Could you email a screenshot of the error to hello@tinytax.co.uk?
That’ll let us pinpoint the cause and give you a precise fix.

In the meantime, please double-check:

The Companies House code is exactly 6 characters

The Company UTR is exactly 10 digits

All dates are completed correctly

Thanks—we’ll get back to you as soon as we see your email.

Best,
Tim
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Dayo Ogunseye 10 Nov 2025 at 17:06
Thanks, I’m at the submission stage and details it’s asking for is the government gateway user id and government gateway password. I have entered the two details correctly so not sure why the problem. Are you suggesting I use the company authentication number? This isn’t what your website is asking for though. Please help
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Dayo Ogunseye 10 Nov 2025 at 17:09
I’ve just sent a screenshot to hello@tinytax.co.uk now as instructed