How Brazilian 13th salary is calculated
The calculation starts with base remuneration, made from monthly salary and the variable-pay average entered by the user.
The tool multiplies that base by the year avos and divides by 12. A month is counted only when it has at least 15 worked days in the informed period.
What avos mean for 13th salary
Avos are 1/12 fractions of Brazilian 13th salary. An employee with 12 avos receives a full gross 13th; someone hired during the year receives the proportion for months that reached 15 days.
First and second 13th salary installments
The first installment is shown as an estimated 50% advance on gross 13th salary.
The second installment starts from the remaining gross 13th salary and concentrates estimated deductions when INSS/IRRF is enabled.
Proportional 13th salary for employees hired during the year
Enter the hire date and reference date to see which months count. Months with fewer than 15 worked days stay out of the avos count.
How INSS and IRRF apply to 13th salary
When the year is 2026, the calculator estimates INSS on 13th salary as a separate base and then estimates IRRF with dependents, alimony, and simplified discount.
For other years, or when legal deductions are disabled, the result remains gross and manual fields can adjust deductions or additions.
Calculator limits
The official value can change because of actual variable averages, absences and leaves, multiple jobs, INSS ceiling use, court-ordered alimony, payroll rubrics, collective agreements, and professional interpretation.
Related calculators
Check other useful calculators for salary, vacation, termination, and financial planning.
Net salary, INSS, income tax, FGTS, proportional 13th salary, overtime, and alimony calculators are also in the backlog.
Important notice
This calculator provides an educational Brazilian payroll estimate, not legal, tax, accounting, or labor advice. Official payslips, eSocial, collective agreements, and professional review prevail.