Tax return 2025: monthly & annual SAT guide for Mexico

Tax return 2025 monthly & annual SAT guide for Mexico
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Introduction

If you issue invoices (CFDI), pay payroll, or charge VAT (IVA), you have periodic obligations before Mexico’s Servicio de Administración Tributaria (SAT, the Tax Administration Service). Filing monthly returns and the annual return correctly and on time is critical to avoid surcharges, updates, and penalties—and to keep your cash flow under control. In this hands-on guide you’ll learn what to file, when to do it, and how to compute your ISR (income tax), IVA (VAT), and withholdings, with clear steps and links to official sources so you can verify each point.

We’ll start with core definitions and the calendar; then we’ll explain tax determination and the step-by-step to submit monthly returns (in the Declaraciones y Pagos service, “DyP”) and your Annual Return. You’ll also find case studies, best practices, and actionable tips you can apply today. Sensitive statements include verification points with SAT, the Federal Tax Code (CFF), the Income Tax Law (LISR), and the VAT Law (LIVA).

Why this article matters to your business

Timely compliance prevents surcharges and penalties, reduces audit risk, and lets you cash in credit balances (for example, automatic ISR refunds for individuals when applicable). Clean compliance also improves your creditworthiness, your relationship with suppliers, and decision-making around pricing and liquidity. The CFF (Federal Tax Code) obliges individuals and companies to contribute and sets sanctions for late or missing returns and for filing after the deadline.

Key concepts: tax return 2025, monthly (provisional/definitive) and annual

What is a tax return?

It is the act through which you report and self-assess federal taxes (ISR, IVA, IEPS, etc.) and, where applicable, withholdings. In Mexico, filing is mainly online via the SAT Portal and Buzón Tributario (SAT’s electronic mailbox), using password or e.firma (advanced e-signature).

Monthly returns (provisional and definitive)

  • Provisional ISR: Corporations (and individuals with business/professional activity outside RESICO) make monthly payments on account of the annual ISR. The LISR sets the mechanics; for corporations the coefficient of profitability from the prior year is used (Art. 14), and those payments are credited against the annual tax.
  • Definitive IVA: Every month you pay the difference between IVA charged (collected) and IVA creditable (paid) under the LIVA.
  • Withholdings: If you withhold ISR (e.g., on wages or “asimilados”) or IVA (cases in LIVA Art. 1-A), you must remit those withholdings monthly.

General deadline: provisional and definitive monthly payments are due no later than the 17th of the following month. If the 17th falls on a non-business day, the deadline moves to the next business day (CFF Art. 12).

Annual Return

  • Corporations (personas morales): the usual deadline is March 31 of the year following the tax year (e.g., tax year 2024 was filed in March 2025). SAT publishes a minisite with guidance and requirements.
  • Individuals (personas físicas): filed in April (usual deadline: April 30), with preloaded income, withholdings, and provisional payments. Automatic refund of ISR may apply when requirements are met.

Note on RESICO for individuals: This regime (LISR, Section IV, Art. 113-E) provides monthly definitive payments, so in general they don’t file the annual ISR return; however, review your specific situation (income, withholdings, other concepts) and SAT’s guidance for RESICO.

Who files and when? Essential calendar

  • Monthly (by the 17th at the latest):
    • Provisional ISR (corporations; individuals not in RESICO).
    • Definitive IVA.
    • Withholdings of ISR on wages/“asimilados” and, where applicable, IVA withholdings (LIVA Art. 1-A).
  • Annual:
    • Corporations: March 31. SAT’s minisite confirms the deadline.
    • Individuals: April 1–30, with preloaded information and possible automatic refunds.

To confirm non-business days and extensions, check the SAT Calendar and the 2025 Miscelaneous Tax Resolution (RMF) in force.

How taxes are determined (ISR, IVA and withholdings)

ISR — Corporations (general regime)

  • Provisional base: taxable income for the period estimating profit via the coefficient of profitability from the prior year (LISR Art. 14).
  • General calculation: estimated profit × ISR rate (annual, pro-rated), minus pending tax loss carryforwards, minus previous provisional payments.
  • Adjustments: in the second half of the year you may request a reduction of provisional payments per LISR and its Regulations (criteria and formal deadlines apply).

Verify: the exact figures and current criteria must be checked in the LISR and its Regulations and/or with your advisor, as reforms may change rules. See the official LISR text (Chamber of Deputies).

ISR — Individuals (business/professional, NOT RESICO)

  • The Law provides monthly provisional payments based on taxable income, authorized deductions, and prior payments. Check LISR Title IV and Regulations for your specific mechanics.

ISR — Individuals in RESICO

  • They pay using reduced rates on income effectively collected; payments are definitive (Section IV, Art. 113-E LISR). Review your case in SAT’s official RESICO guidance.

IVA — Monthly (definitive payment)

  • Determine IVA payable = IVA charged (collected) – IVA creditable (paid) according to LIVA; if applicable, remit withholdings (Art. 1-A).

ISR withholdings on wages and “asimilados”

  • The monthly remittance of ISR withheld from employees is filed through the withholdings return; SAT offers guidance and tools with preloaded data based on payroll CFDI.

Step-by-step: filing monthly returns in DyP

  1. Log in to the SAT Portal and select Declaraciones → Servicio de Declaraciones y Pagos (DyP). Sign in with RFC and password or e.firma.
  2. Choose the period and obligation (provisional ISR, definitive IVA, withholdings).
  3. Capture/verify data: the system offers aids and preloads for certain obligations (e.g., payroll and viewers).
  4. Submit the return and download the acknowledgment (acuse) (and payment reference, “línea de captura,” if there is an amount due).
  5. Pay at your bank or via online banking using the reference within the deadline.
  6. If you spot an error, you can file a supplementary return (“declaración complementaria,” either substitution or correction), following the DyP procedure.

Standard deadline: the 17th of the following month; if non-business, it moves to the next business day (CFF Art. 12).

Tax return 2025 monthly & annual SAT guide for Mexico

Step-by-step: filing the Annual Return

Corporations

  • Prepare your trial balance, work papers, and reconciliations.
  • Visit the Annual Return minisite for companies, review who must file, requirements, and settlement period. Usual deadline: March 31.

Individuals

  • The SAT app preloads income, withholdings, and provisional payments; verify personal deductions (paid by electronic means and with CFDI 4.0) and file in April (deadline April 30).
  • If you have a refund, leverage automatic refunds (meeting requirements) and monitor status in the portal; there are timelines for the authority to process.

Key informative returns (DIOT, withholdings and viewers)

  • DIOT (Informative Return of Transactions with Third Parties): informative VAT report about suppliers. In 2025 SAT communicated a new digital platform to file it and later required exclusive submission through that platform. Verify your obligation and the allowed batch upload specs.
  • Withholdings: SAT provides applications and guides for remitting withholdings (e.g., wages and “asimilados”). Use them to avoid discrepancies.
  • Viewers (annual and monthly):
    • Payroll viewer for employers and for employees;
    • Viewer of invoices issued/received;
    • Viewer of personal deductions.
      These tools help you reconcile figures before filing.

Practical business cases (illustrative)

Figures are illustrative; consult your accountant and verify your facts in Law and the RMF.

Case 1: Trading company (ISR and IVA)

“Comercializadora Alfa, S.A. de C.V.” invoices $1,000,000 + IVA in August and purchases $600,000 + IVA.

  • IVA: charged $160,000; creditable $96,000; payable $64,000 (to be remitted in September, due on the 17th).
  • Provisional ISR: apply the prior year’s coefficient of profitability to cumulative income; subtract previous provisional payments; remit the difference. (See LISR Art. 14 and Regulations for possible reductions in the second semester.)

Case 2: Independent professional (individual not in RESICO)

“Laura,” a consultant, issues CFDI 4.0 for $80,000 in the month. She deducts $15,000 (strictly indispensable expenses with CFDI) and already paid a provisional ISR in prior months.

  • Compute the monthly provisional ISR based on cumulative income, deductions, and prior payments.
  • IVA: charge 16% and credit VAT on expenses that meet requirements; remit IVA payable.

Case 3: Individual in RESICO (services)

“Carlos,” a RESICO designer, collected $50,000 in the month.

  • Compute monthly definitive ISR with the RESICO rate applicable to income effectively collected; being definitive, it is not accumulated for the annual return (except for specific situations or if convenient to file for a refund). Validate your case on SAT’s portal.

Compliance best practices (from official sources)

  1. Check your obligations and data in your Constancia and Viewers before filing (income, withholdings, CFDI). This reduces discrepancies and formal requests from SAT.
  2. Use the official DyP path and keep acknowledgments and payment references (internal control and evidence of compliance).
  3. Monthly VAT reconciliation (charged vs. creditable) and CFDI control with Anexo 20 (receiver fields: legal name, tax regime, postal code) to avoid rejections or loss of deductibility.
  4. Payroll withholdings: review the preload and the payroll viewer before remitting ISR withheld.
  5. Automatic refunds: if you are an individual with an ISR refund, check requirements and timelines for the deposit; track status in the portal.
  6. DIOT: migrate and submit via the new platform to avoid rejections.
  7. Corrections: if you make a mistake, file a supplementary return for correction; know the grounds and avoid repeating errors (the authority may impose penalties for late filing and for supplementary returns that increase contributions).
  8. Keep your Buzón Tributario active and monitored: it is SAT’s official notification channel; configure it and respond to requests on time.
  9. Regularization 2025: if you are behind, review the regularization program in force to reduce penalties/surcharges in cases that meet requirements.
  10. Consult PRODECON: for questions about refunds or administrative actions, their guides and criteria help prevent and resolve contingencies.

Day-to-day, immediately applicable tips

  • Set the 10th of each month as your “tax cutoff” to prepare the return due on the 17th (or next business day).
  • Automate: use calendar reminders and internal flows (e.g., integrating billing and accounting reports) to have CFDI issued/received and payroll ready before filing.
  • Review expense CFDI 4.0: ensure tax regime and postal code of the receiver are correct; without these fields, deductibility/VAT credit may be affected.
  • Simulate your monthly return using viewers; compare against your work papers.
  • Save acknowledgments and payment references per obligation and period (organized digital archive).

Frequently Asked Questions (FAQ)

1) What is the deadline for monthly returns?
Generally the 17th of the following month. If it falls on a non-business day, the deadline moves to the next business day (CFF Art. 12).

2) How do I know if I must file an Annual Return?

  • Corporations: in March (March 31).
  • Individuals: in April (up to April 30); the system preloads income/withholdings and enables automatic refunds where applicable.
  • RESICO individuals: pay definitively each month (Art. 113-E LISR); check whether you must file for other concepts or convenience.

3) What if I make a mistake in a monthly return?
File a supplementary return for correction in DyP. Note that penalties may apply for late filings and for supplementaries that increase tax due.

4) Is the DIOT still required and how do I file it?
Yes. SAT announced—and later confirmed—that DIOT must be filed exclusively through the new digital platform. Review upload specs and validations.

5) How can I verify my CFDI 4.0 are correct for deduction/credit?
Check Anexo 20 and SAT’s guide (requirements like the receiver’s postal code and tax regime). Use viewers and your billing system to detect inconsistencies.

6) How long does SAT take to refund my ISR (individuals)?
If you meet the requirements, automatic refunds apply and there are established timelines (e.g., up to 40 days in certain cases). Track the process in the portal.

7) What records should I keep?
CFDI issued/received, payroll XMLs, acknowledgments and payment references for each obligation, work papers, and reconciliations.

Conclusion and checklist (next week/month)

Key ideas:

  • Anchor on the 17th each month. Use viewers to validate figures before submitting.
  • Compute ISR correctly (coefficient for corporations; Title IV rules for individuals). IVA: charged vs. creditable and withholdings when applicable.
  • Annual: March (corporations) and April (individuals), with preloads and automatic refunds when applicable.
  • DIOT: use the new platform. Supplementary returns: correct formally if you detect errors. Buzón: keep it active and check it regularly.

Checklist for the next week/month:

  1. Schedule the monthly accounting cutoff (the 10th).
  2. Download viewers (payroll, invoices, deductions) and reconcile.
  3. Review CFDI 4.0 (receiver’s data).
  4. Compute IVA (charged vs. creditable) and provisional ISR.
  5. File via DyP and save acknowledgment/payment reference.
  6. If applicable, prepare the Annual Return (corporations in March, individuals in April) and check automatic refund status.

Disclaimer: This material is for information only and does not constitute legal/tax advice. Deadlines and rules may be modified via the RMF or administrative criteria. Always verify with official SAT links and the CFF, LISR, and LIVA, or consult your tax advisor.

Note: Most official resources are published in Spanish by Mexican authorities.

Do you want to file without errors and strengthen your tax and customs compliance?


At Customs Consulting Globa, we help entrepreneurs and SMEs file monthly and annual returns with the SAT, optimize ISR/IVA, automate tasks, and avoid penalties through clear, auditable processes. We integrate your invoicing, accounting, and operational workflows so you can focus on growth.

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