Quoted from GC...
Charging VAT on payments
Payments created in GoCardless are the full amount being charged to the customer. We do not add VAT on top of this. As such, if you do need to charge your customers VAT, you will need to incorporate this into the amount you create your payments for.
Please note that VAT applies to all GoCardless fees from 1 September 2020. Please refer to the VAT FAQs for more information.