I just came across an issue with my first membership

I just came across an issue with my first membership subscription, sales tax - or VAT as I-m a UK company.

I need to charge clients VAT and the current price of 9,99 per month needs to be charged as 9,99 plus 20% vat. I realised this also does not exist in terms of sales tax which IS charged in the US. How do you solve this?

Thanks