How do I calculate the VAT I need to charge on my invoices?

VAT is calculated on the base price of your product or service: you multiply the amount without VAT by the rate that applies in your country (it varies depending on the region and type of goods). For example, if you charge $100 and the rate is 19%, you add $19 to the total you invoice. The important thing is to verify what category applies to what you're selling, because some products have reduced rates or are exempt, so don't assume it's always the same.