If you plan to use TaxCalc (or HMRC Online Services) to submit your clients’ VAT returns, you must sign up for HMRC’s VAT for Agents online service. To do this, read VAT online services for agents and Applying for client authorisation using HMRC Online Services on the HMRC website.

Once you’ve signed up for VAT for Agents, you need to go through the client authorisation process for each client – even if you've already been authorised to act on their behalf using a paper form 64-8.

First, you’ll need the follow details from each client:

• VAT registration number
• postcode of the principal place of business
• effective date of registration for VAT
• final month of the last VAT return submitted to HMRC
• box 5 figure on the last VAT return submitted to HMRC – enter N/A if your client is new to VAT and has not previously submitted a return.

The first three items are on your client’s certificate of registration and, if appropriate, the Notice to file VAT Returns online and pay VAT electronically.

Once you've applied, HMRC will send your client a unique authorisation code. Tell your client to expect this and to pass it to you as soon as they receive it. The code will include the letters VT and expires 30 days from time of issue. If your client doesn’t give you the code in time, you’ll need to start the process again.

When you have the code, log in to your online agent account and enter the code to complete the authorisation process. If you experience any difficulty, check the code before asking HMRC for another.

New VAT clients will normally appear on your VAT for Agents client list within 24 hours of you completing the authorisation process. You can use the service to check the status of online authorisations.

Once you’re authorised to represent a client, HMRC will be able to deal with you direct on specific VAT matters but will continue to send letters about VAT to your client.