HMRC submission error "1046 - Authentication Failure"

How to resolve

1. Check your version number in Sage Accounts by clicking Help then About.
   
   • If your software is compatible, proceed to step 3
2. If you have a Sage Accounts subscription, or if you have Sage Cover Online, Extra or Premium, you can download and install the latest version of Sage 50 Accounts 
   
   If you're not currently entitled to free software upgrades and you'd like to purchase the latest version of Sage Accounts, leave your details and we'll be in touch.
   
   If after updating your software you are still receiving Error 1046. Proceed to step 3.
3. Log in to the Government Gateway and check if the VAT Submission option is available.
4. Delete your eSubmissions Credentials in Settings > Company Preferences > VAT. Select everything in the first box > press Delete > press TAB and Delete until all fields are clear. Enter the credentials again to ensure there are no spaces in the boxes, then try the submission again.
   
   NOTE: If the error occurs when you submit a CIS return, clear and re-enter your CIS details. To do this click Settings then click Company Preferences and click the CIS tab.
   
   If you use Sage 50 Accounts Client Manager and submit on behalf of a client you must also delete the contents in the Accountant tab and enter them again.
5. Check that the Branch Identifier, and for EC Sales the Branch Postcode, are correct. To do this click Settings, then click Company Preferences and click the VAT tab. These details must match what's registered for the company with HMRC.
6. Try entering your HMRC password in capitals.

If the issue still occurs, contact HMRC's Online Service Help-desk on 0300 200 3600 or visit their contact us page for their web chat service at 

https://www.gov.uk/government/organisations/hm-revenue-customs/contact/online-services-helpdesk