Creating an HMRC Application for UK VAT
This process is only necessary in some releases of WHMCS 8.1 and earlier.
The UK left the EU VAT system on 1 January, 2021, separating UK VAT numbers from EU VAT numbering. This separates UK VAT numbers from validation through the VAT Information Exchange System (VIES). Because of this, the UK has released its own online service for UK VAT number validation.
February 5, 2021's patch for WHMCS 7.10 and later updates our VAT tax support to use the new HMRC system for your customers' UK VAT numbers. To continue validating UK VAT numbers successfully, WHMCS users must update the tax configuration in WHMCS for HMRC access. This includes creating an HMRC application through the HMRC Developer Hub and entering the resulting IDs in WHMCS.
Enter an Application name and click Continue.
On the Which APIs do you want to use? page, click Check a UK VAT number. Then, set the toggle to On.
Scroll to the bottom of the page and click Add your application.
To subscribe to the mailing list for the API, select the checkbox and click Continue. If you don't want to receive emails about any APIs, click I don't want emails about these APIs instead.
On the next page, select the topics you want to subscribe to (you must select at least one). Then, click Continue.
On the confirmation page, click View application credentials.
Click Continue. A sandbox Client ID will display. You can safely ignore this since it is not the Client ID that WHMCS uses.
Click Generate a client secret. You can safely ignore this since it is not the Client Secret that WHMCS uses.
Click Get production credentials on the View all applications page and then click Apply for Production Credentials.
After you have your production application, you can retrieve the production Client ID and Client Secret using the links in the side menu.
In the WHMCS Admin Area, go to Configuration > System Settings > Tax Configuration. Then, choose the VAT Settings tab.
Ensure that VAT Mode and VAT Number Validation are both toggled to ON.
Enter your Client ID in Client ID and your Client Secret in Client Secret.
Then, click Save.
For more information on configuring WHMCS for taxes and VAT, see our documentation.