Accounting Checklist for Small Businesses
Monthly, quarterly, and annual tasks every business owner in Mexico should be on top of.
Monthly Tasks
- ✓ Close your books by the 5th of each month
- ✓ File ISR declaration by the 17th
- ✓ File IVA declaration by the 17th
- ✓ Process payroll and pay IMSS by the 17th
- ✓ Reconcile bank accounts
- ✓ Issue and collect all CFDI invoices
- ✓ Review accounts receivable aging
Quarterly Tasks
- ✓ Review P&L vs. budget
- ✓ Assess cash flow for next quarter
- ✓ Review tax payments and estimate next quarter's liability
- ✓ Verify IMSS employee roster is current
Annual Tasks
- ✓ Annual ISR declaration (by April 30)
- ✓ Pay PTU (profit sharing) by May 31
- ✓ Pay aguinaldo (Christmas bonus) by December 20
- ✓ Prepare full financial statements
- ✓ Update corporate books (libro de actas, socios)
- ✓ Review tax planning strategies for next year
- ✓ Backup all digital records (XML files, SAT receipts)
Documents to Keep (5 Years Minimum)
- CFDI invoices (both XML and PDF — XML is required by SAT)
- Bank statements
- Payroll records and CFDI payslips (recibos de nómina)
- SAT acknowledgment receipts (acuses de recibo)
- Contracts and service agreements
- Customs documents if importing or exporting
Common Mistakes to Avoid
- Keeping only PDF invoices. The PDF is a visual representation only. The XML file is the legally valid document for SAT. Without XML, the expense is not deductible.
- Missing monthly filing deadlines. Late filing triggers surcharges (recargos) and penalties that compound monthly. A pattern of late filings increases audit risk.
- Mixing personal and business expenses. Personal expenses in the company account complicate your books and can cause issues during an audit.
- Not registering new employees with IMSS immediately. IMSS registration must happen before the employee's first day — not after. Backdating is not permitted.
- Ignoring platform withholdings. Income from Airbnb, Rappi, Uber, and other platforms is reportable. Withholdings by the platform must be reported and offset in your monthly declarations.
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