Does this tool send my RFC or CURP to any server?

No. The RFC decoder, CURP decoder and ISR calculator all run entirely in your browser using JavaScript. No data is transmitted or stored.

What is the difference between an RFC and a CURP?

The RFC (Registro Federal de Contribuyentes) is your tax ID used with SAT — 13 characters for an individual, 12 for a company. The CURP (Clave Única de Registro de Población) is your 18-character population ID from RENAPO. Both encode your date of birth, but only the CURP encodes gender and birth state.

How do you read date of birth from a CURP?

Characters 5–10 of an 18-character CURP are the date of birth as YYMMDD. Character 11 is H for Hombre (male) or M for Mujer (female), and characters 12–13 are the two-letter birth-state code. This tool reads all of these for you.

What is the homoclave in an RFC?

The homoclave is the two-character code SAT appends before the final check digit to keep RFCs unique when several people would otherwise share the same name-and-date prefix. It is generated by SAT and cannot be guessed from the name alone.

Which tax year does the ISR calculation use?

The tool uses the SAT 2024 monthly ISR tariff published in the Resolución Miscelánea Fiscal, DOF 29-dic-2023. The IMSS employee quota uses the 2024 UMA value of MXN 108.57 per day.

How accurate is the net pay estimate?

The ISR figure matches the official tariff, but the IMSS employee quota is a simplified approximation. Actual deductions depend on your exact salary, benefits (aguinaldo, prima vacacional, etc.) and whether your employer pays full social security. Use the result for guidance and confirm with your payroll department.

Does the calculator include the Crédito al Salario?

Yes. For lower incomes the tool adds the monthly subsidio para el empleo (employment credit) on a simplified schedule and subtracts it from the ISR due, which can reduce or zero out the tax for low earners.

Mexico RFC & CURP Decoder + ISR Net Pay Calculator (2024)

Mexico RFC & CURP decoder with ISR net pay calculator

Three tools in one, all running locally in your browser. Decode your RFC, decode your CURP, and estimate your net take-home pay after Mexican payroll deductions. It is built for employees checking a payslip, HR and payroll staff verifying documents, and anyone who wants to read what their tax IDs actually encode.

How it works

RFC — the tool validates the pattern (3–4 letters, 6 date digits, 3-character tail). For an individual (13 chars) the date sits at positions 5–10; for a company (12 chars) at positions 4–9, read as YYMMDD. It then shows the person type, the decoded date, the two-character homoclave and the final check digit.

CURP — validated as 18 characters. It reads the YYMMDD birth date (chars 5–10), the H/M gender flag (char 11), and the two-letter birth-state code (chars 12–13) from a built-in state table.

ISR net pay — your monthly gross first has a simplified IMSS employee quota removed (roughly 2.85% plus 0.4% on the part above three monthly UMA). The remaining taxable base is run through the SAT 2024 monthly ISR tariff (a fixed fee plus a marginal rate per band), the Crédito al Salario is added back for lower incomes, and the result is your estimated net.

Example

For a monthly gross of MXN 15,000:

Line	Amount
Gross	MXN 15,000.00
IMSS employee quota	− ~MXN 440
ISR withholding	− ~MXN 1,480
Net pay (approx.)	~MXN 13,080

The exact figures appear live as you type, along with the effective tax rate.

ISR 2024 monthly bands (lower limit → rate)

Monthly base (MXN)	Marginal rate
0.01 – 746.04	1.92%
746.05 – 6,332.05	6.40%
6,332.06 – 11,128.01	10.88%
11,128.02 – 12,935.82	16.00%
12,935.83 – 38,177.69	17.92%
38,177.70 – 72,887.50	21.36%
above 324,645.20	35.00%

Privacy: your RFC, CURP and salary never leave your browser. Estimates are for guidance only and do not constitute tax advice.