This tool does the arithmetic on the figures you enter. It does not know your business, the country you trade in, or which rate applies to what you sell, and it does not give tax, accounting or legal advice.
You remain responsible for choosing the correct VAT treatment, numbering your invoices in line with local rules, and keeping the records your tax authority requires. When a situation is unusual — cross-border supplies, exemptions, margin schemes — check with an accountant or your tax authority.
Amounts are rounded to whole cents per line and per VAT rate. Rounding conventions vary between jurisdictions, so compare the totals against your bookkeeping before sending an invoice for a large amount.