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Authentication failing while submitting to CT600
Trying to submit CT600 with HMRC, inputting gateway ID, UTR and password, it continues generates an error authentication failed. I have checked and confirmed details are correct, when I login directly on HMRC website, it has 2 factor authentication, thought it does not ask on tinytax. Can you please help
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Having a Government Gateway account isn't enough on its own - you need to specifically add Corporation Tax as a service. Here's how to check and fix this:
1. Log in to your HMRC business tax account at https://www.gov.uk/log-in-register-hmrc-online-services
2. Look for "Corporation Tax" in your list of services
3. If it's not there, you'll need to enroll - click "Get access to a tax, duty or scheme" and select Corporation Tax
4. You'll need your Company UTR to enroll
5. HMRC will post an activation code (usually 7-10 working days)
6. Once you receive it, activate the service in your account
After Corporation Tax is fully activated, TinyTax will be able to submit your CT600.
Regarding 2FA - the HMRC submission API works differently from web login, so you won't be prompted for 2FA during the TinyTax submission. The Gateway ID and password are sufficient once enrollment is complete.
"Corporation Tax
We cannot display your Corporation Tax details. You may still be able to use the Corporation Tax online service.
You may also still be able to complete your Corporation Tax return."
Service was activated yesterday morning and it does allows me to navigate to use CT submission. Not sure if external submission API system is different and if it takes time to sychronise servers/databases.
Thanks
The message you're seeing - "We cannot display your Corporation Tax details" - suggests the enrollment may not have fully propagated to HMRC's API systems yet. You activated on Christmas Day, so there may be a delay with their backend systems syncing during the holiday period.
A few things to check/try:
1. **Wait 24-48 hours** - Sometimes the web portal works before API access is enabled. Try again tomorrow.
2. **Verify the UTR is linked** - In your HMRC account, check that the company UTR (42*******79) is properly associated with Corporation Tax. Sometimes the UTR needs to be entered during enrollment.
3. **Check credentials carefully** - Ensure there are no leading/trailing spaces in the Gateway ID or password when entering them in TinyTax.
4. **Agent access** - If you're using an accountant's Gateway credentials instead of your own, ensure they have authorization to file for this specific company.
Your accounts submission went through fine (different system), so there's nothing wrong on our end - it's specifically the HMRC Corporation Tax authentication.
Please try again after 24 hours and let me know if it still fails.