Applying retention taxes on an invoice
Quaderno supports any withholding tax required on an invoice. A withholding tax (retention) is an income tax amount that your customer retains on your behalf.
Your customer will pay this tax amount to the government directly. This tax amount is deducted from the total amount your customer pays you.
Retention taxes are negative taxes. For example, if you have to collect retentions in Spain (aka IRPF), you need to apply two taxes to each invoice: VAT 21% VAT and -15% retention tax.