Common MTD VAT errors

Article ID: 2971
Last updated: 05 May, 2023

When processing MTD VAT returns, there are 4 common errors that users may encounter. HMRC believe these 4 errors alone account for 90% of errors encountered by end users. The information relating to the errors and possible ways to resolve have been listed below.

Error 8508 - The VRN specified [XXXXXXXXX] was not found.

Error 500 - Internal Server Error

Error 404 - Not Found

Error 403 - (Client or Agent not authorised) or (Forbidden) TAX_PERIOD_NOT_ENDED

HMRC's customer support model

Error 8508

8508 - The VRN specified [XXXXXXXXX] was not found. This means one of two things  

  • you are enrolled for MTD VAT returns but have attempted to file a non-MTD VAT return. (See below screenshots) or
  • the VRN number has been input in an incorrect format.



To try and resolve this error, we recommend completing the below steps:

Please can you check the following:

  1. Open the client in Practice Manager.
  2. Select Business on the left hand side and open the applicable business details on screen.
  3. Check the VRN does not have any spaces or country initials (such as GB) in it.
  4. Please check the box ‘enrolled for MTD VAT’ is ticked.
  5. Save the changes.

After this is complete please do the following:

  1. Open the client in VAT Filer.
  2. Delete any pre-created or fetched outstanding periods.
  3. Fetch VAT Period.
    1. If you have not previously fetched, you will be prompted to authorise TaxCalc to Connect to HMRC.

Note if you are getting an error for EC Sales List Invalid Registration number, you need to see the link for EC Sales List - Invalid VAT Registration Number

Error 500

For more information on the Error 500 - Internal Server Error, please see the link for Error 500 (Internal Server Error) when fetching for MTD VAT Returns

Error 404

HMRC comments are:

We have observed a steadily increasing number of 404 ‘Not Found’ responses as sign ups to MTD increase. Our investigation has established, the majority of these responses are being returned correctly and it is normally where a user is calling for pre MTD information.

MTD APIs only call data relating to MTD, the user’s historical information will remain visible via the legacy channel (by using your government gateway login).

Therefore, when completing the request to fetch for VAT periods we recommend ensuring that the Open (Outstanding VAT Returns) radio button is selected instead of Open and Fulfilled (Outstanding and Submitted VAT Returns).

If the error occurs with this option selected, the only other issue is that a restriction implemented from HMRCs server could have been met. This would be an intermittent issue which should be corrected when you try again after approx. 10 minutes.

Please note, if you are getting the 404 error for tax returns, you need to look at the link for HMRC Fetch API - Taxpayer data not found. Error: 404

Error 403

For more information on this error, please see the link to the article for 403 Error when attempting to fetch for MTD VAT returns or alternatively the following articles may be useful depending on your setup.

What to do when receiving error 403 (Client or Agent not Authorised) - Practice User

What to do when receiving error 403 (Client or Agent not Authorised) - Individual user

HMRC do not provide a telephone support structure to assist end users with MTD VAT queries. If you do attempt the above steps and the error has not been resolved, you should go to the link for Get help using VAT online services

Article ID: 2971
Last updated: 05 May, 2023
Revision: 11
Views: 6807
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Also read
item EC Sales List - Invalid VAT Registration Number
item HMRC Fetch API - Taxpayer data not found. Error: 404