UDI and UMA explained: Mexico's two reference units

The UMA: who sets it and why it exists

Article 26, part B of the Constitution says that the statistics body (INEGI) calculates “el valor de la Unidad de Medida y Actualización”, used as a unit of account, index, base, measure or reference to determine the amount of obligations in federal and state laws. A constitutional decree of 27 January 2016 created it to detach such amounts from the minimum wage. Its third transitory article provides that every reference to the minimum wage as a unit of account “se entenderán referidas a la Unidad de Medida y Actualización”, in federal and state laws alike.

INEGI’s press release 1/26 of 8 January 2026 gives the update mechanism: the previous year’s value is multiplied by one plus the year-on-year change in the consumer price index (INPC) for December. The change for 2026 is 3.69 %. The monthly value is the daily value times 30.4, and the annual value is the monthly value times 12 (decree, fifth transitory), which gives the figures above.

The UDI: who publishes it and how it moves

The 1995 decree (DOF, 1 April 1995) states that obligations to pay sums in pesos may be denominated in a unit of account called the Unidad de Inversión, “cuyo valor en pesos para cada día publicará periódicamente el Banco de México en el Diario Oficial de la Federación”. Obligations in UDIs are settled in pesos by multiplying the number of UDIs by the value of the unit on the day of payment. The unit’s changes must follow the consumer price index.

Banxico publishes the values in table CP150 ahead of time (on 15 October 2026 its table already ran to 25 October), and the Diario Oficial de la Federación lists them day by day. For 15 October 2026 the value is 8.856094. The value for a different day must be read from the table for that day.

A UDI loan therefore has a balance that rises with inflation; a peso loan has a fixed nominal balance. This explains why the same home may appear with different “starting” payments in the two products. I make no comparison of rates between them, since I found no official source for that.

Where property law uses them

• Sale of a primary residence, income tax. Article 93, section XIX(a) of the Ley del Impuesto sobre la Renta exempts the gain on selling the taxpayer’s casa habitación if the consideration “no exceda de setecientas mil unidades de inversión” and the transfer is formalised before a fedatario público (notary). Using the 15 October 2026 UDI as a calculation, 700,000 × 8.856094 gives about MX$6.2 million (MX$6,199,266). The limit moves with the UDI, so recalculate at the sale date. The conditions are in the home sale exemption guide.
• Deed formality. The Código Civil Federal (arts. 2317 and 2320) uses 365 times the daily minimum wage as a threshold for private-document sales; under the 2016 decree this reads as 365 UMA, a calculation of 365 × 117.31 = MX$42,818.15. Above it, a public deed is required in the federal code, but each state has its own civil code; see the deed guide.
• Public housing credit. The Fovissste law (arts. 178 and 180) lets a worker choose whether the credit is defined in UMA or pesos; see Fovissste. The 2016 decree (sixth transitory) also caps how fast the older Infonavit and Fovissste balances indexed to the minimum wage can be updated: not above the growth of the UMA in the same year.
• Fees and fines. Many state and municipal fees are written in UMA multiples. Which multiple applies depends on the state or municipality; always check its law.

How to use this in practice

When a contract or law quotes a figure in UMA, multiply by the daily value in force on the relevant date (MX$117.31 until the next update in February 2027, which I cannot yet state). When it quotes UDIs, multiply by the UDI of that day. Write the date next to every converted amount.

Which professional to consult

A notary or a real estate lawyer can tell you which unit your state’s fee schedule uses. See notaries and real estate lawyers.