Before you start

A CURP — the RFC is generated from it
Legal status permitting work, if you will be on a Mexican payroll
A comprobante de domicilio under three to four months old
Passport and resident card
For anyone earning in the United States: an accountant who handles both systems, engaged before you move

Step-by-step

1
Register the RFC once the CURP exists
Inscribe yourself in the Registro Federal de Contribuyentes on the SAT portal using the CURP, or at a SAT appointment with ID and proof of address. Salaried people register under sueldos y salarios; your employer can also register you in bulk.
OnlineWho: You or your employer's payroll teamOnline, often under an hourFree
2
Get the e.firma and the Constancia de Situación Fiscal
The e.firma digital certificate requires one in-person SAT appointment with fingerprints; the Constancia downloads instantly afterwards. HR, banks and landlords all ask for the Constancia, so treat it as a standing document you refresh rather than a one-off.
In personWho: YouOne appointmentFree
3
If you are independent, look hard at RESICO
The Régimen Simplificado de Confianza taxes an individual's gross receipts at 1% to 2.5% of ISR, on a band scale, up to an annual ceiling of MXN 3.5 million, with monthly filings and no deductions. It must be elected, it excludes some situations, and exceeding the ceiling drops you out of it from the following month.
OnlineWho: Self-employed individualsElected on registration or at the start of a year
4
If you run a business here, check whether the border-zone stimulus applies to you
The Decreto de estímulos fiscales región fronteriza norte lets qualifying taxpayers with an establishment in the border municipalities apply a credit worth half the general 16% IVA rate — an effective 8% — and an income-tax credit that produces an effective 20% ISR rate. It was published in December 2018, has been extended repeatedly, and the current extension published in the DOF on 31 December 2025 runs it to 31 December 2026. It is not automatic: first-time applicants and renewers alike must file a notice with SAT, with a deadline of 31 March for the year in question. Missing that notice costs you the whole year's benefit.
OnlineWho: Businesses and some independent taxpayers with a border-zone establishmentNotice due 31 March each year
5
Understand what actually makes you a Mexican tax resident
Contrary to the day-count rule people repeat, article 9 of the Código Fiscal de la Federación turns on where your casa habitación is. If you also keep a home abroad, Mexico looks at your centre of vital interests — deemed to be here if more than half your income in the year is Mexican-source, or if the main centre of your professional activities is in Mexico. For a Tijuana resident working in San Diego that test can point either way, and the answer determines which country taxes what.
OnlineWho: You
6
If you earn in the United States, get proper cross-border advice before the first payday
A person living in Tijuana and working in San Diego is inside two tax systems at once, and the US–Mexico tax treaty, the foreign tax credit and US state tax rules interact in ways that are not obvious. California in particular does not follow every federal treaty position. This is the one item on this page where the correct action is to pay a professional who does both sides, and to do it before the arrangement starts rather than at filing time.
In personWho: Cross-border earnersBefore your first cross-border payday

Documents you’ll need

CURP
Passport and resident card
Comprobante de domicilio
RFC, Constancia de Situación Fiscal and e.firma
Border-zone stimulus notice acknowledgement, if you claim it
US wage and withholding documents, if you earn there

Things most newcomers don’t know

The border zone runs an 8% VAT, which changes prices, pricing strategy and where people shop.

Under the northern border stimulus decree, qualifying businesses established in the border municipalities apply a credit equal to half the 16% general rate, producing an effective 8% IVA. That is a visible difference in retail prices against the rest of Mexico and a real competitive factor for any business you might start here. It also means an invoice from a Tijuana supplier and one from a Guadalajara supplier are not comparable at face value. The decree has been extended repeatedly rather than made permanent, and the current extension runs to 31 December 2026 — so treat it as a policy you must re-check annually, not a fixture.

Source: DOF — Decreto de estímulos fiscales región fronteriza norte

The stimulus is opt-in with a 31 March deadline, and missing it costs the year.

Both first-time applicants and existing beneficiaries must file a notice with SAT to apply the ISR credit, and the deadline for the year is 31 March. Businesses that assume last year's registration carries forward automatically lose the benefit for twelve months with no remedy. If you incorporate here, this belongs on the same list as the annual return.

Source: SAT / DOF decree

Baja California charges employers 4.25% payroll tax, among the highest rates in Mexico.

It never appears on an employee's payslip — impuesto sobre nóminas is an employer cost — but it is part of why the true cost of a Tijuana hire is higher than a Puebla or Monterrey one at the same salary. If you are negotiating an offer, or costing a small business, the gap between Baja California's 4.25% and the 3% charged in Jalisco, Puebla or Nuevo León is a real number.

Source: Impuesto sobre nóminas 2026, rates by state

Living here and working there means two tax systems, and the treaty does not make the problem go away.

Cross-border earners have to determine residency under Mexican domestic law and under the treaty, work out which country has the primary claim on employment income physically performed in the United States, and then use foreign tax credits to avoid double taxation — while remembering that US states do not always follow federal treaty positions. It is genuinely complicated, it is the normal situation for tens of thousands of people here, and it is the wrong thing to improvise. Budget for an accountant who does both.

Source: PwC Worldwide Tax Summaries / US–Mexico tax treaty

Common mistakes to avoid

Assuming the border-zone stimulus applies automatically, or that last year's notice carries forward.
Comparing a Tijuana price or invoice against a central-Mexico one without accounting for the 8% IVA.
Registering as a general-regime taxpayer without checking whether RESICO fits.
Assuming a day count decides your tax residency — Mexico looks at your home and your centre of vital interests.
Starting a US job while living here without cross-border advice, and discovering the state tax position at filing time.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.