Before calculating a monthly tax return, your accountant needs more than a folder of invoices: an inventory showing what happened, what is supported and what still needs clarification. An invoice's issue date helps locate it, but does not by itself determine its treatment for the month. An organized handoff links documents to transactions and helps prevent an invoice from appearing twice or a payment received against an older invoice from being overlooked.
Separate tax obligations from your handoff method
Original Fintax Instagram publication about documents needed to prepare a monthly return.
Articles 28, 29, 29-A and 30 of Mexico's Federal Tax Code, or CFF, govern accounting records, tax receipts and document retention. A folder with an index, consistent filenames and version control is an operational recommendation, not a mandatory format established by those articles. Its purpose is to make the tax documents and supporting records relevant to your activity easy to locate.
Send the XML files for issued and received CFDIs, Mexico's electronic tax receipts. Use PDFs as reading aids, not as substitutes for the tax files. A PDF is a visual representation; the XML contains the receipt's structured data. To control duplicates and replacements, record the UUID and the receipt's status alongside the filename. This organization supports review of the documentation requirements in CFF articles 29 and 29-A.
The package should explain the period, not collect files
| Input | Risk if missing | Handoff detail |
|---|---|---|
| Issued and received XML files | Duplicates or unidentified receipts | Index with UUID, date, issuer, recipient and status |
| Receipts and payments | Assigning transactions to the wrong month | Date, amount, related receipt and payment complement where applicable |
| Complete bank statements and cash log | Unexplained transactions | Classify business transaction, own-account transfer or loan and attach support |
| Cancellations, replacements and earlier open items | Using the wrong version or losing follow-up | Link original and replacement UUIDs; identify the open issue and owner |
| Payroll, where applicable | Incomplete documentation for the activity | Receipts and supporting records identified by period |
The connection between a tax receipt and a transaction matters for VAT, known as IVA in Mexico. Article 1-B addresses consideration effectively collected, while article 5 establishes conditions for claiming input VAT, including effective payment of the VAT. Holding a CFDI is insufficient; not every bank outflow produces creditable VAT either. Provide evidence of receipt or payment and explain the transaction, rather than treating a transfer between your own accounts as a purchase. See VAT Law articles 1-B and 5.
For income tax, or ISR, first identify the tax regime. For individuals carrying on business or professional activities, article 105 imposes deduction conditions, including effective payment. Under RESICO for individuals, article 113-E calculates ISR on income effectively collected, excluding VAT and without applying deductions. Sending expense documents therefore does not mean every expense can be deducted. Your accountant must apply the relevant treatment under Income Tax Law articles 105 and 113-E.
Example: handing over September records in October
Assume an individual provides services, issues an invoice in August and receives full payment by bank deposit in September. In September, the individual also receives a PDF of a supplier invoice that remains unpaid. The September document package is being prepared in October. The tax regime has already been identified, but the accountant still needs to review the receipts and applicable conditions.
The package includes August's XML, September's deposit and the link between them, plus the payment complement where applicable. The receipt of payment must not disappear because the invoice was issued earlier: effective collection matters for VAT and, depending on the identified regime, ISR. The supplier invoice is flagged as awaiting its XML and payment, without assuming a VAT credit or deduction. These treatments require review of VAT Law articles 1-B and 5 and Income Tax Law articles 105 and 113-E.
Five controls before approving the calculation
- Create a folder for each period with a file index, handoff date and named person responsible.
- Gather XML files, complete bank statements, the cash log and supporting records. Include earlier documents linked to the month's receipts or payments.
- Compare UUIDs to detect duplicates. Keep cancellations identified and link each replacement to its original receipt.
- Create an open-items list showing the missing document, transaction, possible period, owner and next action. Separate these cases from confirmed information.
- Confirm in writing the version ready for calculation and its exceptions. Afterwards, log each new file, what it corrects and who validated the change.
An open item is not permission to guess
Separating an unresolved case from confirmed information is a workflow control, not an automatic tax exclusion. The accountant must resolve its treatment before finalizing the calculation.
The confirmation might state: September package, version 2, August invoice payment included, supplier invoice awaiting clarification. Keep the accountant's response and the evidence used with the index. If documents arrive after the return has been filed, log the change and request a review of whether it affects the filed information and whether an amended return is appropriate. Receiving a new file does not automatically require a correction.
Frequently asked questions
Is sending PDFs enough?
For this handoff process, send the XML files too. If one is missing, flag it as an open item and request the file; do not describe the package as complete. PDFs make documents easier to read but do not replace the structured data needed to review the receipt.
Should I include invoices from earlier months?
Yes, when they help explain receipts, payments or corrections for the period. Link them to the current transaction and identify their issue month so they are not mistaken for new transactions.
Who confirms that the package is ready?
As a recommended control, the person handing over the package confirms the documents and facts supplied; the accountant confirms receipt, exceptions and the tax treatment reviewed. The record should identify a specific version, rather than giving blanket approval to everything sent.
