How the Mexico resico calculator is verified

Inputs

Input	Field	Type
Annual income collected (MXN)	`annualIncome`	number

The formula

Each derived value below is computed by the Valem engine from the expression shown, in this order. Nothing else runs — there is no hidden code path.

Derived value	Field	Formula (JSONata)
Monthly Income	`monthlyIncome`	`$round(annualIncome / 12, 2)`
ISR rate (%)	`isrRatePercent`	`$round((monthlyIncome <= $const.m1 ? $const.r1 : (monthlyIncome <= $const.m2 ? $const.r2 : (monthlyIncome <= $const.m3 ? $const.r3 : (monthlyIncome <= $const.m4 ? $const.r4 : $const.r5)))) * 100, 3)`
ISR / year	`isr`	`$round(annualIncome * isrRatePercent / 100, 2)`
Net income / year	`netIncome`	`$round($max([0, annualIncome - isr]), 2)`

Rates and thresholds

The expressions above read these as $const. They are the figures the annual refresh replaces, so they live as data rather than being written into the formulas — which is what makes a year-on-year change a one-line diff instead of an edit to arithmetic.

Constant	Value
`m1`	25000
`m2`	50000
`m3`	83333
`m4`	208333
`m5`	291667
`r1`	0.01
`r2`	0.011
`r3`	0.015
`r4`	0.02
`r5`	0.025
`annualCap`	3500000

Test vectors (3)

Every case is executed against this model on each build, by the Java engine and independently by a JavaScript one. A mismatch of a single cent fails the build, so the page cannot ship advertising a figure the model no longer produces.

Case 1 — 600,000 MXN collected — a typical full-time freelancer

given `annualIncome`	600000
expect `monthlyIncome`	50000
expect `isrRatePercent`	1.1
expect `isr`	6600
expect `netIncome`	593400

Case 2 — 240,000 MXN — the lowest 1% band

given `annualIncome`	240000
expect `monthlyIncome`	20000
expect `isrRatePercent`	1
expect `isr`	2400
expect `netIncome`	237600

Case 3 — 3,000,000 MXN — near the ceiling of the regime

given `annualIncome`	3000000
expect `monthlyIncome`	250000
expect `isrRatePercent`	2.5
expect `isr`	75000
expect `netIncome`	2925000

Sources

SAT — Régimen Simplificado de Confianza para personas físicas · checked 2026-08-22
Tabla ISR RESICO 2026 — tasas del 1% al 2.5% por ingreso mensual · checked 2026-08-22

Check it yourself — and reuse it

The whole model as JSON — inputs, outputs, formulas, vectors and sources in one re-runnable document.

This model is published under CC BY 4.0: use it, adapt it, build on it, with attribution. The licence covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds are law, and nobody licenses those; the sources above are where they come from.

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