If you are checking your May 2026 monthly taxes, find the return acknowledgment and any payment receipt first. The general filing deadline was June 17. Which income tax and VAT returns you needed depends on your activity, regime and registered obligations.
If the date has passed, review the evidence
For a past filing date, use this checklist to confirm what was actually submitted and paid. Save the acknowledgment, payment proof and the reconciliation for the period, then note whether a supplementary return is pending. The article remains useful as a post-filing control, not only as a deadline reminder.
A federal decree may add business days based on the sixth numeric digit of the RFC. That extension does not apply to every filing, so the applicable service and obligation must be checked before treating a later date as timely.
Deadline by RFC digit
| Sixth numeric digit | General extension after June 17 |
|---|---|
| 1 or 2 | One business day. |
| 3 or 4 | Two business days. |
| 5 or 6 | Three business days. |
| 7 or 8 | Four business days. |
| 9 or 0 | Five business days. |
The table reflects the decree's general extension. A sector rule, special payment schedule or different obligation may produce another date.
Records for the May calculation
| Area | May records |
|---|---|
| Issued CFDI | Active invoices, cancellations, replacements, credit notes and payment complements. |
| Collections | Bank deposits, cash receipts, card settlements and customer allocations. |
| Received CFDI | Expense XML, payment evidence and relationship to the activity. |
| Payments | Supplier payments, fees, payroll and tax payments. |
| Withholding | ISR or VAT withheld by customers and withholding made to others. |
| Prior filings | Earlier provisional payments, credit balances and amendments. |
Match each payment to its transaction before calculating tax. An invoice may have been issued in one month and paid in another. A bank deposit may also be a transfer between your own accounts rather than a customer payment. Your regime and the tax being calculated determine how each transaction is treated.
ISR review
For the applicable regime, confirm:
- income included in the period under its collection rules;
- deductions that meet the legal and payment requirements;
- prior provisional payments that may be credited;
- ISR withheld by legal-entity customers;
- losses or other reductions supported by the regime;
- consistency with CFDI and the prefilled form.
RESICO individuals use their own monthly form and rate table. Rule 3.13.7 treats their monthly payments as final for RESICO income. That treatment should not be transferred to another regime.
VAT review
| Review | Evidence |
|---|---|
| VAT transferred and collected | Income CFDI, payment complements and bank receipts. |
| Input VAT actually paid | Supplier CFDI, payment and activity support. |
| Withheld VAT | CFDI and withholding records. |
| Different rates or exempt activities | Transaction detail and tax-object fields. |
| Prior credit balance | Earlier return and reconciliation. |
An expense CFDI alone does not establish that input VAT was actually paid or that the purchase meets the credit requirements.
Prefilled data
Compare the amounts SAT has filled in with your records. Look for:
- canceled CFDI still reflected in the period;
- collections received in another month;
- payment complements issued late;
- withholding missing or duplicated;
- expenses unrelated to the registered activity;
- bank deposits that are loans, transfers, capital contributions or other non-sales movements.
Correct the source document or calculation before submitting an amendment.
Filing and payment evidence
| Document | Purpose |
|---|---|
| Tax workpaper | Explains the ISR and VAT figures. |
| Filing acknowledgment | Confirms SAT received the May return. |
| Payment reference | Shows amount and payment validity period. |
| Bank receipt | Proves the bank received payment. |
| Bank statement | Confirms the charge and date. |
The acknowledgment does not prove payment. If tax was due, the payment reference, bank receipt and statement should agree.
If May was not filed
- Confirm the active May obligations in the RFC.
- Reconstruct collections, expenses, withholding and VAT from source records.
- Prepare the return using actual figures.
- Calculate inflation adjustment and surcharges when applicable.
- Submit through the correct individual filing service.
- Pay using a current reference.
- Save the acknowledgment and bank receipt.
Use the actual May figures even if your immediate concern is a missing-return warning. A zero return will not resolve the underlying obligation if your transactions produced tax due.
If May was filed incorrectly
Start with the field that is wrong and the invoice, payment or calculation behind it. Check which amendment type applies and compare the revised result with the original return. After submitting the amendment, pay any difference using a valid reference.
Preserve both acknowledgments and a short note that explains the correction. Review whether the change affects later periods, a credit balance or the tax-compliance opinion.
The guide to checking SAT monthly tax returns explains how to retrieve the filing and payment history.
Official sources
- SAT: business, professional, rental and VAT returns for individuals.
- SAT: RESICO monthly and final returns.
- SAT: federal taxes payable with a payment reference.
- Chamber of Deputies: Income Tax Law.
- Chamber of Deputies: Value Added Tax Law.
Official links to complete the task
Open official services from a new browser tab, confirm the taxpayer and period, and save the resulting acknowledgment or evidence with the case.
