VAT

VAT is TAX on services, and the rate of VAT is currently 20%

The VAT you pay from expenses (input TAX) is deducted from the VAT you charge on your commissions (output TAX), and that is the figure you must pay to HMRC. You usually pay this every three months, but only if you are VAT registered. You only need to be VAT registered when you earn £73,000 or more in a tax year, (that's the gross figure not just your profit.)