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IRRF withholding: taxable base, the deductible portion and deductions

Withholding income tax scares people when they compare the 27.5% rate with their gross salary. But IRRF never falls on the gross: it starts from a base already reduced by INSS, dependents, alimony and pension, and then runs through a progressive table where the number almost every article treats as magic appears, the deductible portion. It is not a bonus or an extra discount: it is the algebraic shortcut that turns the bracket-by-bracket sum into a single multiplication. In this guide we derive that portion by hand, show the 2026 monthly table, explain the R$ 5,000 exemption created by Law 15,270/2025, and separate three things that cause confusion: monthly withholding versus the annual return, the simplified discount versus the legal deductions, and the separate taxation of the 13th salary and accumulated income. Open the [net salary calculator](tool:salario-liquido) alongside as you read, everything runs in your browser.

J-Kit14 min readIntermediate
  • IRRF
  • Income tax
  • Payroll
  • Deductions

Key takeaways

  • The IRRF base is gross minus INSS, dependents, alimony and pension, never the full salary.
  • The deductible portion is not a bonus: it is the algebraic shortcut that replaces the bracket-by-bracket sum with one multiplication.
  • Law 15,270/2025 zeroes IRRF for monthly gross income up to R$ 5,000, with a decreasing reduction up to R$ 7,350, in force since 1 Jan 2026.
  • IRRF is an advance: the monthly withholding is not the tax due, which only settles in the annual IRPF return.

The taxable base is not the gross salary

The first mistake is applying the rate to the full salary. The base for monthly IRRF is gross salary minus the allowed legal deductions. Only after removing all of that does the progressive table come into play. That is why two colleagues on the same salary can carry different IRRF: whoever has more dependents or pays alimony reaches the table with a smaller base.

base = B − INSS − (D × d) − PA − PP
B
the month’s gross salary (plus other taxable income)
INSS
official social-security contribution withheld in the month
D × d
number of tax dependents times the deduction per dependent (R$ 189.59)
PA
alimony paid under a court decision or homologated agreement
PP
deductible private pension (PGBL), within the legal limit
The base for monthly IRRF. Each subtracted item pushes the salary into a lower bracket of the table.
  • Gross salary
  • − the month’s INSS contribution
  • − R$ 189.59 per tax dependent
  • − court-ordered alimony and deductible pension
  • = IRRF taxable base

Since INSS enters this calculation first, it helps to understand the INSS progressive table before computing IRRF: the social-security deduction is itself progressive, and it opens the base subtraction. If you want the whole payslip assembled, the guide on how to compute net salary chains INSS and IRRF in the right order.

The progressive table and deriving the deductible portion

On the base you apply the monthly progressive table, updated by Law 15,191/2025 and in force in 2026. It is bracket-based, each slice of the salary pays its bracket’s rate. But nobody computes it that way in practice: they use a shortcut. You apply the rate of the bracket the base fell into to the whole base and subtract the deductible portion. The point almost no article explains is where that number comes from. It was not invented: it is exactly what is left when you rewrite the bracket-by-bracket sum as a single multiplication.

Monthly IRRF table in force in 2026, Law 15,191/2025. Values in reais.
Monthly base (R$)RateDeductible portion (R$)
Up to 2,428.80Exempt—
2,428.81 to 2,826.657.5%182.16
2,826.66 to 3,751.0515%394.16
3,751.06 to 4,664.6822.5%675.49
Above 4,664.6827.5%908.73
parcela(k) = alíq(k) × início(k) − Σ [ alíq(i) × largura(i) ], i < k
parcela(k)
deductible portion of bracket k
alíq(k)
rate of the bracket the base fell into
início(k)
lower bound of bracket k (where it starts)
largura(i)
width of each bracket i below k
Σ
sum over all brackets i below k
The hidden identity: the deductible portion of bracket k is the tax the single multiplication over-charges in the lower brackets, which is why it must be handed back. Sum bracket by bracket or multiply and subtract the portion: the result is the same number.

Sounds abstract? It gets concrete in the arithmetic. Take a base of R$ 3,500.00, which falls in the 15% bracket. Sum bracket by bracket and then use the shortcut, the two paths must give exactly the same tax. And at the end, watch where the 394.16 portion actually comes from:

Base de cálculo: R$ 3.500,00   (faixa de 15%)

Método 1, somando faixa a faixa (marginal)
  faixa isenta:  0%    x 2.428,80              =    0,00
  faixa 7,5%:    7,5%  x (2.826,65 - 2.428,80) =   29,84
  faixa 15%:     15%   x (3.500,00 - 2.826,65) =  101,00
  imposto = 0,00 + 29,84 + 101,00             =  130,84

Método 2, atalho (aliquota x base - parcela)
  imposto = 15% x 3.500,00 - 394,16
          = 525,00 - 394,16                   =  130,84   <- identico

De onde vem a parcela de 394,16 (faixa de 15%)?
  parcela = 15% x 2.826,65 - [ 7,5% x (2.826,65 - 2.428,80) ]
          = 423,9975 - 29,84                  =  394,16
Worked example 1, both methods give R$ 130.84, and the deductible portion drops out of the sum of the lower brackets itself.

The same rule generates every portion in the table: 182.16 in the 7.5% bracket, 394.16 in the 15% one, 675.49 at 22.5% and 908.73 at 27.5%. None is arbitrary, each is the sum of what the lower brackets would have charged had you applied the full rate to everything. Grasping this kills two common fears: that crossing a bracket makes the whole salary pay 27.5% (only the slice above the limit does), and that the portion is a government favour (it is just accounting).

Exemption up to R$ 5,000 and the transition band

On top of the classic table there is, since 1 January 2026, a new layer. Law 15,270/2025 (sanctioned on 26 November 2025) created a reducer that zeroes IRRF for anyone with monthly gross income up to R$ 5,000. Between R$ 5,000.01 and R$ 7,350.00 there is a transition: the reducer shrinks linearly as the salary rises, until it disappears. That is why you can earn above the old exemption limit (R$ 2,428.80) and still pay zero IRRF. The reducer does not change the table, it is applied afterwards, shaving the already-computed tax.

redução = 978,62 − 0,133145 × R (para 5.000,01 ≤ R ≤ 7.350,00)
R
monthly gross taxable income
978,62
constant coefficient set by the law
0,133145
linear coefficient (slope of the reducer’s decline)
The Law 15,270/2025 reducer in the transition band. It is subtracted from the tax already computed by the table. At R = 5,000 it is worth R$ 312.89 (the maximum); at R = 7,350 it hits zero. For R ≤ 5,000 the tax is fully zeroed.

The most interesting practical consequence is the effective-rate curve, IRRF divided by gross salary. It stays at zero up to R$ 5,000, jumps in the transition band (where each extra real loses a slice of the reducer) and then climbs slowly, always below 27.5%. The top marginal rate is 27.5%, but the effective one only approaches it at very high salaries, because the exempt bracket and the deductible portions hold the average down:

0%6.29%12.57%18.86%25.14%3,00026,50050,000Monthly gross salary (R$)Effective rate
Effective IRRF rate by monthly gross salary (no dependents, 2026 table). Zero up to R$ 5,000; a jump in the transition; a slow approach, never reaching, 27.5%.
View the data
xValue
3,0000%
5,0000%
6,0006.42%
8,00012.97%
10,00015.7%
15,00019.63%
20,00021.6%
30,00023.57%
50,00025.14%

Legal deductions and the simplified discount

The base can be reduced by two paths, and the taxpayer keeps whichever yields less tax. The first is the legal deductions, added item by item. The second is the monthly simplified discount of R$ 607.20 (25% of the exempt-bracket ceiling), which replaces all the legal deductions at once, the INSS included. Payroll computes both and uses the more favourable one.

Tax dependent, R$ 189.59/mo
Each dependent accepted by the tax authority (children, spouse, parents under certain conditions) removes R$ 189.59 from the base. The tax rules are not the health-plan or HR ones.
Alimony
Deductible when set by a court decision or homologated agreement. With no court order, it does not enter the base.
Official pension (INSS)
The month’s contribution. It is the first deduction from the base and is usually the largest for formal employees.
Private pension (PGBL)
PGBL contributions are deductible up to 12% of annual gross taxable income (Law 9,532/1997), on the complete return. VGBL does not deduct.
Simplified discount, R$ 607.20/mo
Replaces all the legal deductions. Only worth it when the legal deductions add up to less than R$ 607.20.

Legal deductions win when…

  • INSS + dependents + alimony + PGBL add up to more than R$ 607.20.
  • This is the case for most formal employees: INSS alone already exceeds R$ 607.20 at higher taxable salaries.

Simplified wins when…

  • The legal deductions add up to less than R$ 607.20 (few dependents, low INSS, no alimony).
  • Common for income with no INSS withholding or with small deductions.
Salário bruto: R$ 8.000,00   (acima de R$ 7.350 -> sem redutor)

Caminho A, deducoes legais
  INSS do mes                        =    921,51
  base = 8.000,00 - 921,51           =  7.078,49
  IRRF = 27,5% x 7.078,49 - 908,73   =  1.037,85

Caminho B, desconto simplificado (R$ 607,20)
  base = 8.000,00 - 607,20           =  7.392,80
  IRRF = 27,5% x 7.392,80 - 908,73   =  1.124,29

Vale o MENOR imposto -> Caminho A: R$ 1.037,85
Economia por escolher certo: 1.124,29 - 1.037,85 = 86,44
Worked example 2, R$ 8,000 salary, no dependents. Both paths are computed; the one with less tax wins.

Notice what settles the contest: not the salary, but the size of the deductions. Here the R$ 921.51 INSS alone already beats the R$ 607.20 simplified discount, so the legal deductions win. For someone on the same salary but with no INSS withheld and no dependents, the simplified would come out ahead. Adding dependents or alimony only strengthens the legal-deductions side.

IRRF is an advance: withholding, adjustment, 13th and RRA

The IRRF withheld each month is an advance, not the tax due. The following year, the annual adjustment return (the IRPF) adds up your income and deductions for the whole year and recomputes the tax: if you withheld too much, you get a refund; if too little, you pay the difference. Confusing the monthly withholding with the final tax is the third classic mistake, and it changes how you read the payslip and plan the return. Some income, though, escapes this annual reckoning and is taxed separately, straight at source.

IRRF (monthly) vs IRPF (annual return)

IRRF is the at-source withholding, month by month, on the monthly table. IRPF is the annual adjustment, on the annual table, that consolidates everything. Withholding is a monthly estimate of what you owe; the adjustment corrects the estimate. Anyone with deductions payroll did not know about (medical expenses, a dependent added later, PGBL) tends to recover tax on the return.

To project the year’s reckoning, use the annual income-tax calculator; to see where IRRF shows up on the payslip, the guide on how to read and check a payslip points to the right line.

13th salary: exclusive, separate taxation

The 13th salary is taxed exclusively at source and separately: it is not added to the month’s salary for the IRRF calculation. It has its own base (13th minus the INSS on the 13th and minus dependents) and its own application of the table. Being exclusive at source, the 13th and the tax withheld on it do not enter the annual adjustment, neither to raise tax nor to trigger a refund.

That is why December seems to charge two different IRRFs: one on the salary and another, separate, on the 13th. The 13th-salary guide details the calculation and the deadlines.

RRA: accumulated income received at once

When you receive at once amounts referring to several past months, back pay from a labour suit, a benefit review, salary differences, throwing it all onto a single month’s table would inflate the rate artificially. Article 12-A of Law 7,713/1988 fixes this: RRA is taxed exclusively at source by a table proportional to the number of months the payment refers to.

In practice: divide the total (minus deductions) by the number of months to find the monthly average, apply the table to the average and multiply back by the number of months. The RRA income-tax calculator runs this and compares it with ordinary taxation, which is sometimes more favourable.

PGBL: the 12%-of-taxable-income cap

PGBL contributions cut the IR base, but with a cap: 12% of annual gross taxable income (Law 9,532/1997), and only for those filing the complete return (with legal deductions). Above 12%, the excess does not deduct. VGBL is not part of this, it is treated differently at withdrawal.

Compute and check it in practice

The theory holds better when you watch the calculation run on your own salary. The tool below assembles the payslip in the right order, progressive INSS, base, table with the deductible portion and the Law 15,270/2025 reducer, and shows the net. Change the gross, add dependents and watch the base drop a bracket:

Simulate net salary with 2026 INSS and IRRF, in your browser, sending nothing.Open the tool full page

With the result on screen, use the checklist below to inspect your own payslip line by line. Most payroll errors surface exactly in these checks:

  • Does the INSS withheld match the month’s progressive table?
  • Is the IRRF base gross minus INSS and deductions, not the full gross?
  • Is each declared dependent removing R$ 189.59 from the base?
  • With gross up to R$ 7,350, was the Law 15,270/2025 reducer applied?
  • Do the 13th and vacation appear in a separate IRRF calc, not added to the salary?

Frequently asked questions

Where does the IRRF table’s deductible portion come from?
It is pure algebra. Computing the tax by summing bracket by bracket gives the same result as multiplying the whole base by the bracket’s rate and subtracting a fixed value. That fixed value, the deductible portion, is exactly what the single multiplication over-charges in the lower brackets. In the 15% bracket, for instance, the 394.16 portion equals 15% of 2,826.65 minus what the 7.5% bracket had already charged.
Does someone earning R$ 5,000 pay IRRF in 2026?
No. Law 15,270/2025 zeroes IRRF for monthly gross income up to R$ 5,000, in force since 1 January 2026. Between R$ 5,000.01 and R$ 7,350.00 there is a decreasing reducer; above R$ 7,350.00, the full table applies with no reduction.
Simplified discount or legal deductions: which one?
Whichever yields less tax. Payroll compares the sum of the legal deductions (INSS, dependents, alimony, pension) with the R$ 607.20 simplified discount and uses the larger deduction. For most formal employees, INSS alone already beats R$ 607.20, so the legal deductions win. The simplified pays off when deductions are small.
Does moving up a bracket make the whole salary pay more tax?
No. The table is marginal: only the slice of the salary above the bracket limit pays the higher rate. That is exactly what the deductible portion guarantees, it hands back the excess charged on the lower brackets. Earning R$ 1 more and crossing a bracket never leaves you with less money in hand.
Why is the 13th’s IRRF separate from the salary?
Because the 13th salary is taxed exclusively at source: it is computed apart, with its own base and its own application of the table, and is not added to the month’s salary. Being exclusive, the 13th and the tax withheld on it do not enter the annual adjustment return, neither to pay more nor to refund.
Is the monthly withholding the tax I actually owe?
No. IRRF is an estimated advance, month by month. The tax due only settles in the annual adjustment return, which sums the whole year’s income and deductions. If payroll withheld more than owed, you get a refund; if less, you pay the difference. Deductions payroll did not know about (medical, PGBL, dependents added later) usually generate a refund.

Start from the base (gross minus INSS, dependents, alimony and pension), apply the table and read the deductible portion as the algebraic shortcut it is, not a bonus. Remember the exemption up to R$ 5,000 and the transition to R$ 7,350, choose between legal deductions and the simplified discount by the lower tax, and handle the 13th and RRA in a separate calculation. Above all: the monthly withholding is an advance, the annual return settles the account.

Sources & references

  1. Law 15,191/2025, monthly IRRF progressive table
  2. Law 15,270/2025, R$ 5,000 exemption and IRPF reducer
  3. Receita Federal, computing the IR reduction from 1 Jan 2026
  4. Law 9,250/1995, deductions, dependents and the IRPF base
  5. Law 7,713/1988, art. 12-A, accumulated income (RRA)
  6. Law 9,532/1997, 12% cap for private-pension deduction

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