Calculadora do Simples Nacional
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Alíquota efetiva = (RBT12 × alíq_nominal − dedução) / RBT12
About this calculator
The Simples Nacional Calculator estimates the effective monthly tax rate for micro and small businesses under Brazil's simplified tax regime. It uses the gross revenue accumulated over the last 12 months (RBT12) and applies the brackets from Annex I (commerce) to calculate the amount due. The result serves as a reference for financial planning and compliance verification.
The calculation follows the formula: effective rate = (RBT12 × nominal rate − deductible amount) / RBT12. The nominal rate and deduction vary by revenue bracket, ranging from up to R$ 180,000.00 to R$ 4,800,000.00. The result is multiplied by the monthly revenue to obtain the tax for that month.
Use this calculator to simulate scenarios before issuing invoices, check if switching tax regimes is worthwhile, or plan business growth. It is especially useful for online stores, boutiques, markets, and other commerce activities under Annex I. Remember that the calculation is an estimate; the official calculation must be done in the PGDAS-D system.
Caveats: this calculator only considers Annex I (commerce). If your activity is industry (Annex II) or services (Annexes III to V), use the specific calculator for the correct annex. Also, the RBT12 must include all taxable revenues without deductions. Errors in RBT12 can distort the rate. Consult an accountant for validation.
Frequently asked questions
What is RBT12?
RBT12 is the total gross revenue accumulated over the last 12 months prior to the calculation period. It is the basis for determining the tax bracket in Simples Nacional.
How do I know if my business falls under Annex I?
Annex I is for commerce (buying and selling goods). If your activity is exclusively selling products without manufacturing or services, you are in Annex I.
Does this calculator replace an accountant?
No. The calculator is an estimation tool. The official calculation must be done in the PGDAS-D system with the help of an accountant, especially to avoid classification errors.
Can I use this calculator for services?
No, it is exclusive to Annex I (commerce). For services, use the calculator for Annex III, IV, or V, depending on the activity.
What if the calculated rate seems wrong?
Check if the RBT12 is correct and if the activity is indeed commerce. If doubts persist, consult an accountant.