If you use No VAT then it will gross up the transaction which will be wrong.I agree it will not fully be 20% of the VAT in boxes 1 & 4 due to reverse charge, ex...

According to HMRC box 6 and 7 are just as important as box 1 and 4 as this determines if you have paid 20% of your sales over to them!Why cannot there be an adj...