Key facts at a glance
Top ISR band
35%
above $425,642/yr
Bottom ISR band
1.92%
up to $10,135/yr
IMSS
Not modeled
several sub-items, UMA-based caps
Here's the number before the mechanics: on a $600,000 salaried sueldo, $109,294 goes to federal ISR, leaving $490,706 a year ($40,892/month), an effective rate of 18.2%, before IMSS employee contributions come off on top.
Most confusion about a Mexican payslip comes from treating ISR as a single flat percentage, when it's actually a progressive monthly table with 11 bands, each with its own cuota fija (fixed base amount), and then wondering why IMSS isn't explained the same way, it genuinely can't be, since it's split across multiple sub-items with different bases entirely.
See your own ISR breakdown, band by band.
Open the Mexico calculatorHow the SAT tarifa mensual actually works
The SAT publishes a monthly bracket table in Anexo 8 of the Resolución Miscelánea Fiscal: 11 bands running from 1.92% (income up to $844.59/month) to 35% (above $425,642/month, cumulative for the year when annualized). Each band lists a límite inferior, límite superior, cuota fija, and porcentaje. To calculate your ISR for a given month, find your band, take that band's cuota fija, and add the percentage applied to whatever portion of your income sits above the band's floor. That's your monthly withholding; multiply by 12 for a close annual estimate (this calculator does the annualization for you).
This is structurally the same idea as US or UK progressive brackets, just with a slightly different presentation, a pre-computed cuota fija instead of asking you to sum every lower band's tax yourself. Only the income inside each band is taxed at that band's rate, which is why your effective rate always lands below your top marginal band.
IMSS runs on a separate track entirely. It covers enfermedad y maternidad, invalidez y vida, cesantía en edad avanzada y vejez, and other sub-items, several of which use the UMA (a government-published reference value, not your actual salary) as their base, each with its own cap. There's no single IMSS percentage the way there's a single ISR percentage per band, which is exactly why this calculator, and most single-number online tools, either omit it or quietly get it wrong.
ISR at three salary levels
Federal ISR shown alone, since IMSS isn't a single clean rate to add on top.
| Gross salary | ISR | Net take-home | Effective rate |
|---|---|---|---|
| $300,000 | $41,420 | $258,580/yr ($21,548/mo) | 13.8% |
| $600,000 | $109,294 | $490,706/yr ($40,892/mo) | 18.2% |
| $1,200,000 | $284,833 | $915,167/yr ($76,264/mo) | 23.7% |
Figures use the 2026 SAT tarifa mensual, annualized, ISR only. Run your own exact salary through the Mexico Salary Calculator.
Why IMSS is left out, and what it actually costs you
IMSS employee contributions are real money out of every paycheck, but they're split across several sub-items with different bases and caps, several tied to the UMA rather than your salary directly. Approximating that as a flat percentage risks a genuinely wrong number, especially near the caps, so this calculator scopes to ISR only rather than guess.
In practice, expect your real net take-home to land somewhat below the ISR-only figures shown here and in the calculator, the exact gap depends on your salary level and which IMSS sub-items apply at your income.
Aguinaldo and PTU: taxed separately, not part of this calculator
Aguinaldo, the mandatory year-end bonus (at least 15 days' salary), has its own partial tax exemption, up to 30 days of the UMA, with the excess taxed separately from ordinary monthly salary. PTU (participación de los trabajadores en las utilidades, employee profit-sharing) follows a similar but distinct exemption rule.
Neither is included in this calculator's annual salary figures, which model your ordinary monthly sueldo run through the ISR table 12 times, not the separate one-off calculations these bonuses trigger.
Run your own numbers, band by band
Enter your salary to see exactly how much goes to ISR, and where your take-home actually lands.
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Frequently asked questions
What exactly is ISR, and how is it different from IMSS?
ISR (Impuesto Sobre la Renta) is Mexico's federal income tax, calculated on your taxable salary through progressive monthly bands published by the SAT (Servicio de Administración Tributaria), from 1.92% up to 35%. IMSS (Instituto Mexicano del Seguro Social) is a completely separate set of contributions that funds healthcare, disability, retirement, and other social security benefits, split across several sub-items (enfermedad y maternidad, invalidez y vida, cesantía en edad avanzada y vejez, and more), each with its own base and cap tied to the UMA (Unidad de Medida y Actualización). They're deducted from the same paycheck but calculated on entirely different rules.
Why does this calculator not include IMSS?
Because IMSS employee contributions aren't a single clean rate the way ISR is. They're split across multiple sub-items, several of which use the UMA rather than your actual salary as their base, with different caps on each. Approximating IMSS as a flat percentage would risk giving you a materially wrong number, so this calculator scopes to ISR only and flags the gap clearly rather than guessing.
How does the SAT tarifa mensual actually work?
The SAT publishes a monthly bracket table (currently 11 bands, from 1.92% up to 35%) in the Anexo 8 of the Resolución Miscelánea Fiscal. Each band has a límite inferior, límite superior, a cuota fija (a fixed base amount), and a percentage. Your ISR is the cuota fija for your band plus the percentage applied to the amount of your monthly income above that band's floor. This calculator annualizes the result by running your salary through the monthly table and multiplying by 12, which is mathematically equivalent to how payroll actually withholds it month by month.
What's the difference between my marginal ISR band and my effective rate?
Your marginal band, the highest one shown in the calculator's bracket breakdown, is the rate applied to your next peso of income, not your whole salary. On a $1,200,000 salary, you reach the 30% band, but your effective rate, ISR ÷ gross salary, works out to only about 23.7%, since the bands below 30% only tax the portion of income that falls inside them.
Does aguinaldo (the year-end bonus) get taxed the same way as regular salary?
No. Aguinaldo has its own partial exemption, up to 30 days of the UMA is tax-exempt, with the excess taxed separately from your regular monthly salary. PTU (employee profit-sharing) has a similar but distinct exemption rule. Neither is included in this calculator's annual salary figures, which model ordinary monthly salary only.
Is this calculator accurate for 2026?
It uses the 2026 SAT tarifa mensual (Anexo 8, Resolución Miscelánea Fiscal), applied monthly and annualized, for federal ISR on salaried income (sueldos y salarios). It doesn't model IMSS employee contributions, aguinaldo, PTU, or the subsidio al empleo (a small credit for lower-income workers). Always confirm with the SAT or a tax professional for your exact position.