June brings a date that many individuals leave until the last minute: the monthly declaration for May. If you have business activity, professional services, leasing, or VAT to review, the point is not just to log into the portal and submit numbers. The important work happens beforehand: cross-check CFDI, banks, collections, expenses, withholdings, and working papers so you don’t file a declaration you later have to correct.
If the deadline passed, audit the filing
Confirm what was actually filed and paid for the period: return, acknowledgment, payment reference, bank proof and the reconciliation behind ISR, VAT and withholdings. If a difference remains, record whether it requires an amended return or only better evidence. The checklist stays useful as a post-filing control after June 17.
The SAT sheet for business activities, professional services, leasing, and VAT indicates that submission is monthly and sets the 17th day of the month following the period as a reference. For May 2026, this makes it important to review the information before June 17, not on the night of the same day.
Calendar Alert
If your RFC qualifies for a sixth-digit facilitation, confirm the exact day on the portal or with your accountant. Even so, work as if the deadline is the 17th: this leaves room to resolve discrepancies.
Quick traffic light before submitting
| Situation | Practical interpretation | Recommended action |
|---|---|---|
| Everything matches | CFDI, banks, and taxes explain the same period. | Submit and save acknowledgment, capture line, and working papers. |
| There is a minor difference | The data has explanation and locatable support. | Document the cause before submitting. |
| There is a material difference | It may affect ISR, VAT, withholdings, or deductions. | Stop submission and review with tax criteria. |
| Support missing | The number may be correct, but it cannot be proven. | Obtain XML, bank statement, or receipt before closing. |
What is advisable to review before entering the portal
- CFDI issued in May: valid invoices, canceled, replaced, and credit notes.
- CFDI received: deductible expenses, payment method, CFDI usage, and operation support.
- Banks: deposits, commissions, payments to suppliers, own transfers, and unidentified movements.
- VAT: charged, paid, creditable, and differences due to partial payments or pending invoices.
- ISR: taxable income, deductions, withholdings, and previous provisional payments.
- Receipts: prior returns, payment references, payments, and complementary returns if any.
Mistakes that make a simple tax return costly
| Common mistake | How to prevent it |
|---|---|
| Reporting income only based on deposits | Cross-check bank statements against issued CFDI and payment methods. |
| Claiming VAT credit without full support | Review CFDI, payment, relation to business activity, and documentation. |
| Ignoring canceled invoices | Separate canceled, replacement invoices, and credit notes before calculations. |
| Using figures from memory | Work with worksheets, not quick estimates. |
Why this review matters even if the portal preloads data
Preloaded information helps but does not replace your control. The portal may show CFDI and relevant data, but you need to know if an invoice was actually collected, if an expense truly applies, if a withholding is correctly applied, or if a deposit is not income. Without this review, the system becomes a calculator with incomplete data.
If you detect discrepancies this week
- Do not submit the return just to clear the pending status.
- Identify if the difference comes from CFDI, bank, VAT, withholding, or accounting classification.
- Keep evidence: XML, PDF, bank statement, contract, payment receipt, or explanation of the transaction.
- Decide whether to correct before filing or if it requires tax authority guidance.
- Leave a closing note so the next month does not start with the same question.
Minimum file you should be able to open later
- Final worksheet with figures used for ISR and VAT.
- Folder of issued, received, canceled, and replacement CFDI.
- Bank statement for the period with marked or reconciled transactions.
- Declaration receipt, payment reference, and payment proof if applicable.
- Brief note of differences, decisions made, and pending items for the next month.
That file is not bureaucracy. It is what allows you to explain a return months later, when no one remembers why a deposit was not income, why an expense was not credited, or why an invoice was replaced.
A well-prepared monthly return does not start at the submit button. It starts when your CFDI, banks, and criteria tell the same story.
— Fintax
How Fintax can help
Fintax can help you prepare the monthly closing with review of CFDI, banks, VAT, ISR, and supporting documentation. The goal is to file on time, but also to file with peace of mind and sufficient evidence if a difference needs to be explained later.
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.
