Simulate the gross and net amounts of the Brazilian 13th salary bonus.
The Brazilian 13th salary (gratificação natalina), guaranteed by Law 4.090/1962 and regulated by Decree 57.155/1965, is paid in two installments across the year. The first, settled by November 30, equals half the gross salary and is paid with no income-tax withholding. The second, paid by December 20, is based on the amount proportional to the months worked (avos) and deducts the INSS computed on the full 13th plus the IRRF assessed on the 13th itself. This calculator reproduces the math step by step: it multiplies the gross salary by avos/12 to reach the gross 13th, splits off the 1st installment (50%, no IR), applies INSS and IRRF over the base (gross 13th minus INSS, minus R$189.59 per dependent, minus alimony), and shows the net second installment and the net total for the year. It is an educational simulation based on the official 2026 tables (INSS via Portaria MPS/MF 2/2025; IRRF via Laws 15.191/2025 and 15.270/2025), handy for checking your pay stub or planning year-end spending.
The gross 13th comes from a simple formula: gross salary divided by 12 and multiplied by the months worked (avos). Each complete month (or a fraction over 15 days) counts as one avo; a worker present the whole year adds up 12 avos and receives the full 13th. The 1st installment is always half of that gross and, by law, is paid with no income-tax deduction.
The deductions show up in the 2nd installment. INSS applies to the full gross 13th (not to the half), and IRRF is computed on the base left after subtracting the INSS, the R$189.59 per-dependent deduction, and alimony. The net second installment is therefore the gross 13th minus INSS, minus IRRF, minus the 1st installment already advanced.
Example 1 (illustrative values), a R$ 3,000 salary with 12 avos: the gross 13th equals the salary, R$ 3,000, and the 1st installment paid in November is R$ 1,500 with no IR. In the 2nd installment, INSS is deducted from the R$ 3,000 and IRRF from the base after INSS; at lower salaries the tax can be small or zero, since the current table grants an effective exemption up to R$ 5,000.
Example 2 (illustrative values), hired in July, 6 avos, a R$ 3,600 salary: the proportional 13th is R$ 3,600 × 6/12 = R$ 1,800, with a 1st installment of R$ 900. Entering dependents and alimony lowers the IRRF base in the 2nd installment. The figures are rounded only to show the mechanics; run the calculator with your real salary for the exact amount.
The 13th is owed to formally registered employees (CLT), domestic workers, and INSS retirees and pensioners; freelancers and PJ contractors do not receive a 13th by law. FGTS also applies to the 13th: the employer deposits 8% of the amount into the worker's linked account, just as with the monthly salary. The deadlines are strict, 1st installment by November 30 and 2nd by December 20, and collective agreements may bring them forward but never delay them.
The INSS and IRRF tables are adjusted periodically, so this tool uses the 2026 rules cited in the source and carries the educational-simulation notice. Situations such as leaves of absence, habitual bonuses, commissions, and other variables can change the 13th's base and are not covered here. For the official amount on your pay stub, confirm with HR, the payroll department, or an accountant.
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></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
Avos are the monthly fractions that make up the 13th: each complete month worked in the year is worth 1/12 (one avo), and a fraction of 15 days or more within a month also counts as a full avo. Someone who worked the whole year accumulates 12 avos and receives the full 13th, while someone who worked part of the year receives it proportionally. The calculator uses that number to multiply the salary by avos/12 and reach the gross 13th.
⚠️ Educational simulation. The 1st installment has no income-tax deduction. The 2nd installment has INSS and IRRF for the December period.
2026 tables: INSS, Portaria MPS/MF 2/2025. IRRF, Law 15.191/2025 and Law 15.270/2025 (exemption up to BRL 5,000 gross).
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