vatcalc onl 0

I am a private limited company registered under the VAT Flat Rate Scheme at 7.5% for my retail business. I buy goods at £5, and the supplier does not charge VAT on my goods due to the reverse charge rule. I sell the item for £8, and I add £2 VAT on it, so the customer finally pays me £10. Under the Flat Rate Scheme, I pay 7.5% of the total amount I charge from the customer (£10), which means I pay £0.75 to HMRC. To check whether my invoice amounts are correct or not, I used VATCalc.Onl to easily add or remove VAT from the final amount.