Do you know exactly how much you pay in taxes in Mexico based on your monthly salary? Most Mexican workers have a general idea of their tax obligations but aren’t familiar with the specific details that could help them better optimize their personal finances.
Income Tax—known in Mexico as ISR (Impuesto Sobre la Renta)—is the main tax that affects your paycheck. Depending on your income level, taxes in Mexico can range from full exemption to progressive rates of up to 35% of your earnings. For 2025, the ISR tables establish 11 different income brackets, each with its own tax rate and fixed fee.
In this article, we’ll walk you step by step through how to correctly calculate your taxes, which deductions you can apply, and a few insider tips that are rarely discussed. Understanding this process will not only help you stay compliant with tax regulations but also plan your personal finances more effectively. Let’s dive in!
What Is ISR and How Does It Affect Your Salary?
The Income Tax (ISR) is a federal tax applied directly to income earned by both individuals and businesses in Mexico. Unlike other taxes, ISR applies specifically to earnings after authorized deductions have been applied—commonly referred to as net income.
One of the key characteristics of ISR is its progressive structure. This means that the more you earn, the higher the percentage you pay. For individuals, tax rates range from 1.92% up to 35%, depending on income level. For businesses, however, a flat rate of 30% applies.
If you’re a salaried employee, you’ve probably noticed line items such as “ISR mes” or “ISR withholding” on your pay stub. Previously, this withholding was known as ISPT (Tax on Labor Income). While related, ISPT specifically referred to ISR applied to wages and salaries.
It’s important to note that if you’re employed under a formal payroll system, you don’t need to calculate or pay ISR directly—your employer is legally required to withhold and remit the tax to the SAT on your behalf. Still, understanding how it works helps you better interpret your net salary.
How to Calculate ISR Step by Step in 2026
To calculate your ISR in 2026, you’ll need the official tax tables published by the SAT. The calculation follows a progressive system in which higher income leads to a higher tax rate.
The process for calculating your monthly ISR consists of five basic steps:
✅ Identify your total monthly income (gross salary).
✅ Find your income bracket in the 2026 ISR table, including the lower and upper limits.
✅ Subtract the lower limit from your total monthly income.
✅ Multiply the result by the applicable percentage on the excess.
✅ Add the fixed fee corresponding to your bracket.
Example:
If your monthly income is MXN 20,000, according to the 2025 table you fall into the bracket with a lower limit of MXN 15,487.72, a fixed fee of MXN 1,640.18, and a tax rate of 21.36%.
👉 MXN 20,000 − MXN 15,487.72 = MXN 4,512.28
👉 MXN 4,512.28 × 21.36% = MXN 964.62
👉 MXN 964.62 + MXN 1,640.18 = MXN 2,604.80 in monthly ISR
Keep in mind that you can reduce your tax burden through personal deductions, such as medical expenses, tuition payments, or mortgage interest. These deductions are capped at five UMAs per year (MXN 195,710 in 2025) or 15% of your annual income, whichever is lower.
Tax Tips No One Ever Tells You
Many taxpayers are unaware of legitimate strategies to optimize their tax burden. First, review your tax regime, as choosing the right one can lead to significant savings. For example, the Simplified Trust Regime (RESICO) offers lower rates and simplified payments for eligible taxpayers.
Personal deductions are your best ally. You can deduct medical expenses, tuition, mortgage interest, and retirement contributions. Just remember that these deductions are limited to five UMAs per year (MXN 195,710 in 2025) or 15% of your annual income, whichever is lower.
Additionally, certain types of income—such as public entertainment activities, prizes, and mortgage loan interest—may be exempt from ISR. For payroll income, the Employment Subsidy reduces ISR for lower-income workers.
Did you know you can request a tax refund up to five years later? All you need is a valid e-signature and a recent bank statement with your CLABE number. Refunds typically take around 10 business days, although the SAT legally has up to 40 days to process them.
To avoid costly mistakes, consider hiring an accountant. This professional can save you 8 to 15 hours per week and ensure you stay up to date with SAT requirements.
Conclusion
Knowing how to calculate your taxes in Mexico is a fundamental tool for managing your personal finances. Understanding how ISR works allows you not only to meet your tax obligations but also to legally and effectively optimize your tax burden.
Because ISR is progressive, every additional peso you earn may place you in a different tax bracket. That’s why staying informed about updated tax tables for 2026 is essential for sound financial planning. Personal deductions also represent valuable opportunities that many taxpayers miss simply due to lack of information.
Choosing the right tax regime can result in substantial savings. Regimes like RESICO offer meaningful advantages for certain taxpayer profiles. It’s also important to remember that tax planning is not about evasion—it’s about making smart use of the benefits the law allows.
The next time you review your pay stub, you’ll be able to understand each line item and verify that the calculations are correct. And when it’s time to file your annual tax return, you’ll have the tools to maximize deductions and potentially receive a favorable refund.
Financial and tax education is, without a doubt, a cornerstone of personal economic health. By applying the knowledge shared in this guide, you’ll take a major step toward full control of your finances—while remaining fully compliant with SAT regulations.
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