Why one tax rate cannot always be applied to an entire receipt
A basket containing differently taxed items needs separate tax bases. Multiplying the whole purchase by one item’s rate can overstate or understate the total tax.
Sales tax / VAT / GST →Group items by their actual treatment
Combine items only when they share the same applicable rate and tax-inclusive or tax-exclusive status. Exempt items, zero-rated items and local levies may also need separate treatment under the invoice rules. Do not infer legal classification solely from a product name. The calculator handles one supplied rate at a time rather than identifying the correct rates for a shopping basket.
Calculate two hypothetical lines
Assume item A costs 100 before tax and uses a 5% rate, while item B costs 50 before tax and uses a 10% rate. Their taxes are 5 and 5, making total tax 10 and the final bill 160. Applying 10% to the entire 150 instead would produce tax of 15, an overstatement of 5. These rates are invented for the example, not classifications for real goods.
Add the groups after calculating them
Run each group through the tax calculator and sum the results. A merchant rounding tax on each individual item can differ by small currency units from a calculation rounded only at group level. Whether multiple taxes compound, how shipping is allocated and which items receive a coupon must follow the actual transaction and local rules. Keep those decisions outside the arithmetic rather than hiding them in an unexplained average rate.
Try the calculators
- Sales tax / VAT / GST
Add tax or extract it from an inclusive price.
- Percentage calculator
Find a percentage of any number.
- Discount calculator
Find the sale price and how much you save.