Brazil’s 13th salary: how it is calculated, when it lands, and why the second half is smaller

How the 13th is built month by month

The 13th, legally, the Christmas bonus, does not appear fully formed in December: it accrues over the year. For each month worked, the employee earns 1/12 of their pay, a "twelfth". Work the whole year and you gather 12 twelfths, that is, a full month’s pay; work half a year and you gather 6, and so on. The calculation base is the pay owed in December (or in the month you leave), not January’s salary, so if you were promoted or got a raise during the year, it is the year-end figure that applies to all twelve twelfths.

The word "pay" is bigger than the base salary. Under TST Precedent 45, habitual supplementary work, the overtime that recurs month after month, is part of the 13th. Precedent 347 explains how: you use the physical average, meaning the number of hours actually worked over the year becomes an average that feeds the base. The same logic applies to night-shift premiums, hazard or unhealthiness premiums, and regular commissions. That is why the 13th of someone who works well beyond their hours is usually larger than the flat salary alone, the variable pay enters as an average. To see how these items show up on your payslip, read the guide on how to read and check a payslip.

In a 31-day month the hiring cutoff shifts by a day: starting up to the 17th still yields 15 days worked. In February, the reverse. What always matters is the count: 15 or more days worked in the month. Keep this logic in mind, it comes back when a contract ends mid-year and you need to know how many twelfths the worker takes on severance.

When it lands: the two installments, the deadlines and the law behind them

The 13th was born with Law 4,090 of 1962, which created the Christmas bonus and set the twelfths rule. Three years later, Law 4,749/1965 split the payment into two installments and set the deadlines still in force today. The first installment, the advance, equals half the salary and may be paid between February 1 and November 30 of each year (art. 2). The second, the final settlement, must be paid by December 20 (art. 1), net of the advance already made. If the worker asks in January, the first installment can be brought forward together with vacation pay.

1. 1962Law 4,090

   Creates the Christmas bonus: 1/12 of pay per month of service, a 15+ day month counting in full.

2. 1965Law 4,749 and Decree 57,155

   Split the 13th into two installments and regulate the payment deadlines.

3. Feb 1First-installment window opens

   From here the employer may pay the 50% advance.

4. Nov 30First-installment deadline

   Last day to pay the advance, which is paid gross, with no deductions.

5. Dec 20Second-installment deadline

   Last day for the settlement, which carries the INSS and income tax on the whole 13th.

The deadlines are not suggestions: paying the 13th late, or only in January, is an offense subject to an administrative fine and to double payment in labor claims. Many employers cluster the advance in November to line up with year-end, but the law allows it from February on, common when the worker takes vacation in the first half and requests the advance then.

The two-installment trap: why the second one is smaller

Here is the point that causes the most confusion, and the most "payroll got it wrong" accusations. The first installment is paid gross: half of the 13th, with no deductions at all. Every deduction, the INSS and the income tax, falls only on the second installment, and is computed on the full value of the 13th, not on the remaining half. So: the second installment receives the other half of the gross and, out of it, come the INSS and income tax on the whole 13th. It is mathematically unavoidable that it comes out smaller than the first. The gap between the two installments is, exactly, INSS plus income tax.

Always run the full calculation in the same order. Most mistakes, by whoever computes and whoever checks, come from getting the base wrong, forgetting that the first installment is gross, or adding the 13th to the month’s salary for tax purposes (which you must not do).

1. Build the baseAdd the base salary to the averages of regular extras, overtime, night-shift, unhealthiness and hazard premiums, and commissions (TST Precedents 45 and 347).
2. Count the twelfthsOne twelfth per month with 15+ days worked (Law 4,090/1962, art. 1, § 2). Whole year = 12 twelfths.
3. Compute the gross 13thDivide the base by 12 and multiply by the twelfths. That is the full value of the 13th.
4. Set aside the 1st installment50% of the gross 13th, paid with no deductions by Nov 30.
5. Apply the INSSOn the whole gross 13th, using the year’s progressive table, separate from the month’s salary.
6. Apply the income taxOn (gross 13th − INSS − deductions), using the monthly table; withheld exclusively at source.
7. Close the 2nd installment2nd installment = gross 13th − 1st installment − INSS − income tax, paid by Dec 20.

INSS and income tax on the 13th are calculated separately

The 13th has its own taxation: it is not added to December’s salary to compute taxes. The INSS hits the 13th on its own, the Social Security Regulation (Decree 3,048/1999, art. 214) applies the monthly contribution table to the gross value of the bonus, separate from the month’s salary, without offsetting the first installment. The income tax, in turn, is withheld exclusively at source (Law 7,713/1988, art. 26): the amount enters its own base, with a definitive withholding, and does not join the month’s income or the annual adjustment return. Because each is handled in isolation, the effective rate on the 13th can differ from the one on your ordinary salary.

The INSS is progressive by bracket: each slice of the 13th is taxed at its bracket’s rate, not the whole amount at the top rate, the same logic explained in progressive INSS rates. On whatever remains after the INSS, the income tax applies, using the monthly table with its deductible portion. There is an important relief in 2026: under Law 15,270/2025, anyone with taxable income up to R$ 5,000 is exempt, and that exemption applies to the 13th on its own. In practice, a gross 13th of up to R$ 5,000 pays no income tax; between R$ 5,000 and R$ 7,350 there is a decreasing reduction; above that, the full table kicks in, with a top rate of 27.5%.

Two examples, worked by hand

Nothing beats seeing the whole calculation. Below, two 2026 scenarios, no dependents. The first shows overtime integration and the twelfths rule; the second shows income tax biting the second installment of a higher salary. Every figure matches the 13th salary, full calculation tool, embedded at the end of this section.

Example 1, hired mid-year, with habitual overtime. João was hired on June 3, on a flat salary of R$ 2,500 plus overtime averaging R$ 500 a month. The 13th base rises to R$ 3,000. From June to December there are 7 months with 15+ days, 7 twelfths. The gross 13th is (3,000 ÷ 12) × 7 = R$ 1,750.00. The first installment is half of that: R$ 875.00, paid gross. The INSS hits the R$ 1,750: 7.5% on the first bracket (R$ 1,621.00 = R$ 121.58) plus 9% on what exceeds it (R$ 129.00 = R$ 11.61), totaling R$ 133.19. The income tax is zero: R$ 1,750 is below both the taxable bracket and the R$ 5,000 exemption ceiling. The second installment is 1,750 − 133.19 − 0 − 875 = R$ 741.81, and the net total is R$ 1,616.81. Notice: the second installment (R$ 741.81) already comes in below the first (R$ 875.00), and the gap is exactly the R$ 133.19 of INSS.

Example 2, a salary high enough for income tax to bite. Maria worked the whole year (12 twelfths) on R$ 8,000, no dependents. The gross 13th is R$ 8,000.00 and the first installment R$ 4,000.00. The progressive INSS on the R$ 8,000 sums the four brackets and comes to R$ 921.51. For the income tax, the base is the 13th minus the INSS minus the R$ 607.20 standard deduction (the most favorable option the law allows): 8,000 − 921.51 − 607.20 = R$ 6,471.29. Applying the 27.5% rate and subtracting the R$ 908.73 portion, the income tax is R$ 870.87. The second installment is 8,000 − 921.51 − 870.87 − 4,000 = R$ 2,207.62, and the net total is R$ 6,207.62. Now the contrast is stark: the first installment was R$ 4,000 and the second, R$ 2,207.62, the R$ 1,792.38 gap is exactly the INSS (R$ 921.51) plus the income tax (R$ 870.87).

One detail that trips people up: in Example 2, a payroll that does not use the standard deduction computes income tax on 8,000 − 921.51 = R$ 7,078.49, which yields R$ 1,037.85 of tax and a second installment of R$ 2,040.64. Both routes are legal; the difference is the choice of the standard deduction, and on the 13th that choice is definitive, because the tax is withheld exclusively at source and is not adjusted in the return. That is why two correct calculators can display slightly different figures, which I unpack just below.

Severance, absences and leave: the cases that confuse

When a contract ends mid-year, the proportional 13th joins the severance package. Law 4,090/1962, in art. 3, guarantees the proportional bonus on dismissal without cause, computed on the pay of the severance month. Resignation also entitles the worker to the proportional amount; dismissal for cause does not. And there is a valuable subtlety: with indemnified notice, the notice period projects onto the contract for all legal purposes (CLT, art. 487, § 1; TST Precedent 371), and that projection can add a twelfth to the 13th. For the full severance math, see the severance calculator and the labor termination guide; for the proportional vacation that travels alongside, the vacation-pay calculator.