Accuracy and Methodology

What the tools do

Invoice Generator is operated by Caravaca Labs, LLC. Its calculators perform arithmetic from values that you enter. They do not determine whether a transaction is taxable, select a legally applicable rate, file a return, or replace review by a qualified accountant or tax professional.

Invoice total calculation

1. Subtotal is the sum of quantity multiplied by unit cost for every line item.
2. Percentage tax and percentage discounts are calculated from the subtotal.
3. Total equals subtotal, plus tax and shipping, minus discount.
4. Balance due equals total minus the amount already paid.
5. Displayed monetary values are rounded to two decimal places.

Some jurisdictions require different rounding, tax bases, or line-level treatment. Review the final document against the rules and accounting practices that apply to you.

VAT and sales tax formulas

• Forward calculation: tax = base amount x rate / 100; total = base amount + tax.
• Reverse calculation: base amount = tax-inclusive total / (1 + rate / 100).
• The calculator accepts the rate you provide and does not claim that rate is current or applicable.

Primary tax sources

Confirm rates and applicability with the authority responsible for the transaction. Useful starting points include:

• California Department of Tax and Fee Administration rate lookup
• New York Department of Taxation and Finance rate lookup
• European Union VAT rules and rates

Templates and country pages

Industry and country pages provide editable starting points, not completed compliance documents. Dedicated VAT and GST pages are limited to countries classified under those systems in our maintained country dataset. Requirements can vary by registration status, transaction, customer, product, and location.

Testing and corrections

Automated tests cover document-total invariants and representative forward and reverse tax calculations. We review calculation behavior when those tests or the underlying formulas change. To report a suspected error, use the contact page and include the inputs, expected result, and source supporting the correction. Do not include customer or invoice data in a public report.