Payroll differences rarely show up in the same month: they appear later, as an IMSS assessment, a penalty or an overpayment nobody caught. The best defense is to close every month in the same order. Here is a list of the key checks and the deadline for each.
The checklist
| # | What to check | When |
|---|---|---|
| 1 | Validate the month's payroll CFDI (electronic payslips filed with the tax authority) | Before closing |
| 2 | Reconcile the IMSS (social security) billing against SUA | Before day 17 |
| 3 | Review ISR (income tax) withheld and the monthly adjustment | Before day 17 |
| 4 | Calculate the state payroll tax (ISN) base by state | Per each state |
| 5 | Reconcile Infonavit (housing fund) in bimonthly months | Before day 17 of the odd month |
| 6 | Reconcile the Fonacot (worker consumer-credit fund) statement | Per the Fonacot calendar |
| 7 | Generate the accounting journal entry | At accounting close |
| 8 | Deliver payslips | On payday |
To go deeper on any of them: how to reconcile the IMSS billing with SUA and ISN rates and due dates by state.
Good practices
- Run every check with the same files for the month, so results are consistent with each other.
- Write down each difference you find and how you corrected it.
- Keep a calendar with reminders for each deadline.
Legal basis
- Social Security Law, article 39 (payment of contributions).
- Income Tax Law, article 96 (remittance of withholdings).
- State payroll tax laws.
In Nomikhor, much of this checklist comes out of the same payroll: ISR with monthly adjustment, IMSS and ISN calculated automatically, unlimited stamping, Nomikhor–SUA–IDSE reconciliation, the Fonacot statement, bank layouts for payment and an accounting entry ready for your close.