Mexico's fondo de ahorro: how the savings fund match works and when it is tax-exempt

A fondo de ahorro is a savings fund in which the worker sets aside part of each payslip and the employer deposits the same amount. The Mexico savings fund benefit is one of the country's most common prestaciones (employee benefits) because the employer's match can be free of income tax (ISR) for the worker, excluded from the social-security base, and partly deductible for the company. For 2026, the employer's match is exempt up to 13% of salary or MXN$55,633.03 a year, whichever is lower.

How a fondo de ahorro works: equal deposits, an annual payout, limited withdrawals

Each pay period, payroll withholds the worker's contribution, say 13% of salary, and the employer deposits an equal amount. The fund pays out the balance and its returns once a year, usually in August or December.

The worker's share is a wage deduction under the Federal Labour Law's rule for savings-scheme deductions (LFT Art. 110-IV, written for cajas de ahorro, literally "savings banks", and applied to the fondo in practice). That rule requires the worker's express, freely given consent and caps the deduction at 30% of the amount by which the wage exceeds the minimum wage.

When the employer's match is exempt from ISR

The Income Tax Law (LISR) Art. 93-XI exempts the worker's income from the fund only when the fund meets the employer's deductibility requirements in LISR Art. 27-XI and the Income Tax Regulation (RLISR Art. 49). All of these must hold:

1. The fund is general: offered to all workers on the same terms (for unionised staff, the collective agreement sets those terms).
2. The deposits are equal. The employer contributes the same amount as the worker.
3. The employer's contribution stays within two caps (next section).
4. Withdrawals are limited. RLISR Art. 49-I allows withdrawals only at the end of employment or once a year.
5. The money is used as the regulation requires. RLISR Art. 49-II requires the fund to make loans to participating workers and invest the remainder in registered federal government securities, publicly offered securities, or fixed-income instruments the tax authority (SAT) designates.

When the fund qualifies, the payout (contributions plus returns) is exempt for the worker, whose own contributions were already taxed as salary.

LISR Art. 93 limits the exemption for most previsión social (welfare benefits such as grocery vouchers) once salary plus exempt benefits exceed seven times the annual UMA, the official reference unit (MXN$299,562.48 in 2026): above that line, only one annual UMA of benefits stays exempt, or the amount that brings the total to seven UMA if that is larger. The last paragraph of Art. 93 excludes qualifying savings funds from that overall limit, so for higher earners the fund is tested only against its own caps.

The two caps: 13% of salary and 1.3 times the annual UMA

LISR Art. 27-XI limits the employer's annual contribution to 13% of the worker's salary and 1.3 times the annual reference unit. The statute's text still says "salario mínimo general elevado al año", but the 2016 desindexation reform bars the minimum wage from use as a unit of reference and reads such references as the UMA (Unidad de Medida y Actualización, the reference unit INEGI publishes each January). Federal circuit courts have applied the same reading to the ISR exemption limits in LISR Art. 93. For 2026 the annual UMA is MXN$42,794.64, in force from 1 February 2026, so:

• 1.3 × MXN$42,794.64 = MXN$55,633.03 a year

Whichever cap is lower applies: 13% for anyone earning up to about MXN$35,662 a month (MXN$55,633.03 ÷ 13% ÷ 12), the peso cap above that. The peso cap changes every 1 February with the new UMA.

When a contribution exceeds a cap, practice treats only the excess as taxable salary. LISR Art. 93-XI contains no express excess rule, but RLISR Art. 47 refers to the tax on the excess over the previsión social limits, which supports that reading.

The fondo de ahorro and the SBC: equal deposits, at most two withdrawals a year

The SBC (salario base de cotización) is the wage base for social-security (IMSS) and housing-fund (INFONAVIT) contributions. The Social Security Law (LSS) Art. 27-II excludes the savings fund from the SBC when worker and company make equal weekly, fortnightly, or monthly deposits. If the fund is set up differently, or the worker can withdraw from it more than twice a year, the contributions become part of the SBC.

LSS Art. 27-II sets no cap, so a contribution above the ISR caps is not by itself included in the SBC. The LSS allows two withdrawals a year where the ISR rule allows one, so a plan with one withdrawal a year plus withdrawal at termination meets both rules. Where the employer deposits more than the worker, IMSS's Technical Council treats only the difference as part of the SBC (Acuerdo 494/93 of 18 August 1993, published in the federal gazette (Diario Oficial) on 11 April 1994 under the predecessor law, whose wording Art. 27-II repeats). The Acuerdo is IMSS's administrative position, not statute.

What the employer can deduct: the 53% / 47% rule

Because a qualifying contribution is exempt income for the worker, LISR Art. 28-XXX limits the employer's deduction. The company deducts 53% of the contribution if the exempt benefits it grants did not decrease from the previous year, and 47% if they did.

The part of a contribution above a cap is not deductible, unless the company pays the worker's ISR on that excess and treats the tax as further income for the worker (RLISR Art. 47).

Loans against the fund

RLISR Art. 49-III allows loans secured on the fund, up to the worker's own balance and once a year. If the fund lends to the same worker more than once a year, contributions stay deductible only when the previous loan was fully repaid at least six months earlier.

Worked example: MXN$20,000 a month with a 13% fund

A worker earns MXN$20,000 a month, MXN$240,000 a year. The plan is open to all staff, takes equal monthly deposits, and allows one withdrawal a year plus withdrawal at termination.

Contributions.

• Worker: MXN$20,000 × 13% = MXN$2,600 a month, deducted from pay
• Employer match: MXN$2,600 a month
• Employer total for the year: MXN$2,600 × 12 = MXN$31,200

ISR caps.

• 13% cap: MXN$240,000 × 13% = MXN$31,200. The contribution equals the cap.
• Peso cap: MXN$31,200 is below MXN$55,633.03.
• Result: the full MXN$31,200 is exempt from ISR.

SBC. With equal deposits and limited withdrawals, the employer's MXN$2,600 a month is excluded from the SBC.

Year-end payout. The worker receives MXN$62,400 (MXN$31,200 from each side) plus returns, all exempt.

Employer deduction.

• Exempt benefits did not decrease: MXN$31,200 × 53% = MXN$16,536
• Exempt benefits decreased: MXN$31,200 × 47% = MXN$14,664

A worker on MXN$50,000 a month with the same 13% plan receives an employer match of MXN$78,000 a year. Only MXN$55,633.03 is exempt; the remaining MXN$22,366.97 is taxable salary for ISR on the excess-only reading. The SBC exclusion still applies, since the LSS sets no cap.

Summary

The ISR exemption for a fondo de ahorro requires a plan open to all workers, equal deposits, and withdrawals only once a year or at termination. The employer's contribution must stay within 13% of salary and 1.3 annual UMA (MXN$55,633.03 in 2026). The SBC test is separate: equal deposits and no more than two withdrawals a year, with no cap. The employer deducts 53% of the contribution, or 47% if exempt benefits decreased.

A firm running payroll for many clients has to check every worker against both caps all year and apply the new peso cap each February; in a spreadsheet, one client's update is easy to miss. Flux applies the current UMA cap and the separate ISR and SBC tests to each client's fund on every pay run.