Mexico City concentrates the country's highest density of registered companies and also the highest density of local tax obligations that many business owners ignore entirely. The federal SAT — ISR, VAT, CFDI — is only part of the picture. Companies in Mexico City operate under a second tax layer administered by the City Treasury, with its own deadlines, its own filing systems, and its own penalties. The least known of these local taxes — and the one generating the most silent debts — is the payroll tax.
Mexico City Payroll Tax (ISN): the tax that does not appear on SAT
The ISN is a state-level tax — in this case of Mexico City — on compensation paid to workers providing services within Mexico City territory. The 2026 rate is 3% monthly on total payroll, including regular salaries, commissions, bonuses, pro-rated Christmas bonus, and any cash payments to workers.
It does not appear on the SAT portal (sat.gob.mx) because it is not a federal tax — it is administered through the Mexico City Treasury system (finanzas.cdmx.gob.mx). This detail means many business owners, especially those who register their RFC with help from an out-of-state accountant or through a digital invoicing platform, simply never learn about it.
How to register for Mexico City ISN and file the first return
The ISN registration process in Mexico City is independent of the federal SAT RFC registration and has two stages. First, registration in the Mexico City Fiscal Registry (Padrón Fiscal), completed online at finanzas.cdmx.gob.mx, requiring: RFC, CURP of the legal representative, proof of fiscal domicile in Mexico City, articles of incorporation (legal entities) or official ID (individuals), and a SAT tax compliance certificate. Second, specific enrollment in the ISN registry, selecting the "Impuesto sobre Nóminas" tax and registering the payroll start date.
Once registered, the system generates a monthly payment reference that can be paid at banks or online. The declaration and payment must be completed before the 17th of the month following the payroll period. There are no additional informational returns like the DIOT — just the monthly payment with the period's payroll information.
Commercial property tax (predial) in Mexico City: alcaldías, cadastral values and January discounts
The predial is a local property tax levied on property ownership. For companies that own the property where they operate (not tenants), the commercial predial has considerations different from residential.
Non-residential properties in Mexico City have cadastral values calculated by the Treasury that are typically higher than residential equivalents in the same area. High-demand commercial zones — Polanco, Santa Fe, Insurgentes, Reforma, WTC — have frequently updated cadastral values. The annual predial for a 200 m² office in Polanco can range from $35,000 to $85,000 MXN annually, depending on the age of the cadastral appraisal.
| Item | Residential property CDMX | Commercial property CDMX |
|---|---|---|
| Tax base | Residential cadastral value | Commercial cadastral value (higher) |
| Applicable rate | Progressive schedule in CDMX Fiscal Code | Commercial rate (higher) |
| January payment discount | 7% if full year paid upfront | 7% if full year paid upfront |
| Bimonthly installments | 6 bimonthly options available | 6 bimonthly options available |
| Senior citizen discount | Applies under conditions | Does not apply |
| Non-payment consequence | Surcharges + lien | Surcharges + lien |
Land use for offices in Mexico City: the invisible risk that ends in closure
Land use is the Achilles heel of many companies in Mexico City, especially those renting in mixed-use zones like Polanco, Condesa, Roma Norte, Del Valle, or Cuauhtémoc Centro. The typical situation: the company rents a ground floor or office floor in a building that "operates as an office building" — other businesses work there, the landlord has experience renting to companies — but the property never had its land use changed to commercial or services.
| Land Use CDMX | Commercial offices permitted | Common zones |
|---|---|---|
| CS — Commerce and Services | ✅ Yes | Insurgentes, Reforma, WTC |
| E — Equipment | ✅ Yes (by intensity level) | Polanco, Santa Fe |
| HC — Residential with Commerce | ⚠️ Ground floor only, m² limits | Condesa, Roma, Nápoles |
| H — Pure Residential | ❌ No | Residential throughout the city |
| HM — Mixed Residential | ⚠️ Depends on intensity level | Mixed Cuauhtémoc, BJ areas |
If the land use is not compatible, the company can continue operating as long as no inspection detects it — but remains in permanent risk. When the alcaldía carries out an inspection (following a neighbor complaint, a verification campaign, or randomly), closure can be immediate. The process to obtain a land use change or a CAUS (Land Use Compliance Certificate) takes 2 to 6 months and costs $5,000 to $25,000 pesos in official fees, plus processing fees.
Mandatory electronic accounting in Mexico City: when it applies and what errors SAT detects
Electronic accounting (Art. 28 CFF) requires maintaining XML records and submitting them monthly to SAT via Buzón Tributario. The $4,000,000-peso annual threshold means a high proportion of Mexico City companies — where operating costs are higher and required revenue levels are greater — fall under this obligation without being fully prepared.
SAT automatically cross-references the monthly trial balance against the taxpayer's issued and received CFDIs. If there are discrepancies between income recorded in the accounting and income CFDIs issued, or between expenses recorded and supplier CFDIs, the system generates an alert that can lead to an invitation letter or an electronic review.
In-house accountant vs. external firm in Mexico City: the decision that affects real tax cost
The question of whether to hire an in-house accountant or outsource has a different answer in Mexico City than in other cities, because payroll costs are significantly higher and local obligations (ISN, predial, land use) require specific knowledge that a generalist in-house accountant does not always have.
An in-house accountant in Mexico City with sufficient expertise to handle a legal entity with employees, monthly VAT, ISN, IMSS, electronic accounting, and SAT interactions costs between $23,000 and $45,000 MXN monthly with statutory benefits. The same service scope from an external firm costs between $5,500 and $12,000 MXN monthly in Mexico City. The $15,000–$33,000 MXN monthly difference — $180,000–$396,000 annually — is significant for a growing company. For businesses with annual revenues below $8,000,000 MXN, the cost-benefit ratio rarely favors an in-house accountant.
Frequently asked questions about accounting for companies in Mexico City
What local taxes do companies in Mexico City pay beyond federal ISR and VAT?
Companies with an establishment or payroll in Mexico City face three main local tax obligations, separate from federal requirements. The first is the Payroll Tax (ISN — Impuesto sobre Nómina), administered by the Mexico City Treasury: 3% monthly on total compensation paid to workers providing services within Mexico City territory. It does not appear on the federal SAT portal — it is filed and paid through the CDMX Treasury system (finanzas.cdmx.gob.mx). The second is Commercial Property Tax (Predial Comercial): non-residential properties in Mexico City carry property tax at rates and cadastral values different from residential properties. It is paid annually (or in bi-monthly installments) to the CDMX Treasury. The third is Land Use compliance (Uso de Suelo): not a tax, but the absence of land use classification compatible with business activity can result in closures, fines, and problems with the business license, which in turn affects SAT compliance. Companies in Mexico City that satisfy only federal SAT obligations and ignore local duties accumulate debts with the Treasury that can surface at any time — especially when applying for a Local Tax Compliance Certificate or during company due diligence.
How is the Mexico City Payroll Tax (ISN) calculated and paid?
Mexico City's Payroll Tax is governed by the Fiscal Code of the Federal District and the Law of Finance of the Federal District. The rate is 3% on total compensation including: regular salaries and wages, commissions, bonuses, pro-rated Christmas bonuses (aguinaldo) and vacation pay, and any cash benefits. Employer IMSS contributions are not included in the ISN base (they are deductible for federal ISR but do not reduce the ISN taxable amount). The monthly calculation is straightforward: total monthly compensation × 3% = ISN for the month. To file: log in to finanzas.cdmx.gob.mx → Recaudación → Padrón de Contribuyentes → ISN. The filing deadline is the 17th of the month following the period. In the first quarter of operating with employees, the company must register in the Mexico City Treasury taxpayer registry — a separate process from the federal SAT registration. Non-compliance triggers surcharges of 1.5% monthly on the unpaid balance, plus penalties ranging from $14,880 to $119,040 pesos per fiscal year under the 2026 Mexico City Fiscal Code.
What is "uso de suelo" (land use) and why is it critical for Mexico City offices?
Land use (uso de suelo) is the legal classification of the permitted purpose for a property, regulated by Mexico City's Territorial Ordering Program (formerly PGOEDF) and administered by SEDUVI (Secretaría de Desarrollo Urbano y Vivienda). For a company to legally operate commercial offices in a property, it must have a compatible land use classification: H (mixed residential), HC (residential with commerce), E (equipment), CS (commerce and services) or equivalent. The problem is widespread in areas like Polanco, Condesa, Roma, and Cuauhtémoc: many buildings that appear to be "office buildings" have pure or limited mixed residential land use, and landlords do not always disclose this to tenants. The company operates with an apparent business license but without the correct land use foundation. Consequences include: closure by alcaldía inspection, nullification of the business license (affecting tenders, contracts, and audits), and for REPSE (specialized services) registrations, the non-compliance may invalidate the registration. To verify: the land use program can be checked at seduvi.cdmx.gob.mx by entering the property's exact address. If the land use is not compatible, there are procedures for change or for obtaining a Land Use Compliance Certificate (CAUS) that take between 2 and 6 months.
What are the electronic accounting obligations for Mexico City companies with high revenues?
Electronic accounting is a federal obligation (Art. 28 CFF and Miscellaneous Fiscal Rules) but its practical implications are especially relevant for Mexico City companies that grow quickly toward the thresholds. Required to maintain and submit electronic accounting monthly to SAT via Buzón Tributario: legal entities with annual income above $4,000,000 pesos, individuals with business activity earning above $4,000,000 pesos, and any taxpayers with employees (regardless of income level, for payroll reporting). Electronic accounting requires: chart of accounts in SAT XML format (Annex 24 of the Miscellaneous Resolution), monthly trial balance in XML submitted to SAT, and accounting entries (journal entries) available on SAT request during review. For a Mexico City company exceeding $4,000,000 in annual income, electronic accounting is mandatory from the first month of the fiscal year in which that cumulative income is exceeded. Failure to submit or submitting XML files with formatting errors generates SAT invitation letters and, if persistent, demands with fines of $1,400 to $17,060 per non-compliant period.
How much do accounting services for a company in Mexico City cost in 2026?
The cost of accounting services in Mexico City varies significantly based on transaction volume, number of employees, tax regime, and whether additional services such as auditing or tax representation are required. For a mid-sized company in Mexico City (legal entity, 5-15 employees, ISR + VAT + ISN + payroll + IMSS): a basic outsourced accounting service (monthly returns, payroll calculation, IMSS, ISN, annual return) costs between $3,500 and $8,000 MXN per month at established firms in the city. Firms in Polanco, Santa Fe, and Lomas charge between $8,000 and $25,000 MXN monthly for the same service, with a brand and location premium. A certified in-house accountant (CPA with experience) in Mexico City carries a payroll cost of $18,000 to $35,000 MXN monthly before benefits. With full statutory benefits (IMSS, Christmas bonus, vacation pay, vacation premium) the real cost rises to $23,000–$45,000 MXN monthly. The comparison is not only about price: an in-house accountant cannot cover the filing peak load of the 15th–17th of each month across multiple obligation types, lacks a specialist network for atypical situations (SAT audits, REPSE, tax treaties), and creates key-person risk. For companies up to $8,000,000 MXN annually, outsourcing is typically more cost-efficient.