Written for Mexico. This analysis applies to Mexican federal tax law — ISR (income tax), IVA (VAT) and SAT rules — and cites Mexican statutes. Amounts are in Mexican pesos (MXN).
The contracts, penalties, tax exemptions and credits of this country are not written in pesos: they are written in UMAs, UDIS, minimum wages and reference rates — units that change every year or every day and that most business owners look up third-hand, if at all. Here is the full map: what each indicator is, who officially publishes it, and where it hits you. Every direct look-up link lives in our Resource Center.
UMA — the yardstick for penalties and caps
The UMA (Unidad de Medida y Actualización, the daily reference unit) is calculated and published by INEGI every January (in force from February 1; in 2026: MXN $117.31 per day). Since the 2016 de-indexation, almost every penalty, cap and legal threshold that used to read "minimum wages" now reads UMA: the CFF penalties, the IMSS contribution caps (25 UMA), the art. 93 LISR exemptions (the ~$128,000 for the sale of personal property is 3 annual UMA), the thresholds for vulnerable activities in anti-money-laundering matters. If a legal number matters to you, it is almost certainly stated in UMAs.
Minimum wage — what the UMA no longer is
It is set by CONASAMI (MXN $315.04 general / $440.87 border zone in 2026) and keeps its own territory: wage floors, and the labor concepts that the LFT still anchors to minimum wages — such as the cap on the seniority premium (2 minimum wages). The UMA/minimum-wage confusion is one of the most frequent calculation errors in finiquito (final pay) computations and social-security contributions: each cap has its correct unit, and using the wrong one moves real money.
UDIS — the unit that grows with inflation
The UDI (Unidad de Inversión, the inflation-indexed unit) is published by Banxico daily and tracks the INPC (Mexico's consumer price index). It lives in mortgage loans, in investment instruments — and in the tax system more than you think: the exemption for the sale of a primary residence is 700,000 UDIS (~MXN $6M today, estimated — the UDI floats daily), and tax credits are updated with inflationary mechanics. When the amount of an exemption "rises on its own" every year, that is the UDIS at work.
TIIE and the target rate — the reference price of money
Banxico publishes the target rate (its monetary-policy instrument) and the TIIE (interbank equilibrium rates, now led by the funding TIIE). They apply to you in every variable-rate bank loan, and where no one looks: in the default interest of well-drafted contracts ("TIIE + X points") and in the market-rate support for loans between related parties — the shareholder's loan to their own company at a made-up rate is re-characterizable; the one referenced to TIIE or CETES plus a documented margin is defensible.
CETES and the FIX — reference yield and currency
The CETES mark the risk-free rate in pesos — the minimum benchmark for any investment and another legitimate reference for intercompany rates. The FIX is the official exchange rate whose legal mechanics (art. 8 Monetary Law, art. 20 CFF) deserve their own article: here it is. And for portfolios with precious metals: Banxico publishes the official quotes for its gold and silver coins (Centenario, Libertad ounce) — the serious benchmark against the counter price.
Do your contracts and calculations use the correct units?
This is exactly the kind of detail where cases are won and lost: the interest clause with no valid reference, the final pay capped with the wrong unit, the exemption computed with a two-year-old UDI. At Strategium, contracts and calculations go out with their units, sources and look-up dates documented — precision that later becomes evidence.
Frequently asked questions
Why do the UMA and the minimum wage exist separately?
Because until 2016 the minimum wage was the unit for everything (penalties, credits, caps), which made it impossible to raise without making the whole country more expensive. The de-indexation reform created the UMA for those functions and freed the minimum wage to grow as a wage — which is why, ever since, the minimum wage has risen much faster than the UMA, and why it matters not to confuse them.
Where can I look up all these values in one place?
The DOF publishes a block of indicators daily (FIX, UDIS, TIIE) and each issuer has its own portal (INEGI for the UMA, CONASAMI for the minimum wage, Banxico for the rest via its Economic Information System). Our Resource Center gathers the official links with an explanation of each one.
Which indicator do I use for default interest if my contract says nothing?
In commercial matters, the statutory supplementary interest rate is 6% per year (Commercial Code) — almost always below the real cost of money, which is exactly why an interest clause referenced to TIIE or CETES plus a margin is one of the most profitable lines your contract can have.
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