Written for Mexico. This analysis applies to Mexican federal tax law — ISR (income tax), IVA (VAT) and SAT rules — and cites Mexican statutes. Amounts are in Mexican pesos (MXN).
It's the founding misunderstanding of every new taxpayer: "I had no income, so I don't have to file." False — and expensive. The obligation to file the return arises from your regime, not from your numbers: if you're registered with activity, a month with no movement gets filed too — at zero. It takes five minutes, costs zero pesos, and not doing it sets off a chain of consequences absurdly out of proportion to what avoiding it would have cost.
How to file the monthly zero return
You go into the Declarations and Payments service on the portal of the SAT (Mexico's tax administration) — the direct link is in our Resource Center — with your RFC (federal taxpayer ID) and password or e.firma (the SAT's digital signature), choose the period and your obligations (ISR, IVA, withholdings depending on your regime), and enter the month's reality: no income, no taxable acts — the application itself, now pre-filled with your CFDIs (digital tax invoices), will show you zeros if you truly issued and received nothing relevant. You submit, download your acknowledgment (with no payment line, because there's nothing to pay), and you're done. The deadline: the 17th of the following month — with the little-known gift of the facilities decree: additional business days depending on the sixth numeric digit of your RFC (1-2: one extra day; 3-4: two; 5-6: three; 7-8: four; 9-0: five). The annual zero return works the same way in its own application: you file it by its deadline (March for legal entities, April for individuals), reporting the year with no income — and note: the "zero" annual return of someone who had withholdings or income from other chapters is not a zero return: it's incomplete.
When a "zero" return is a lie (and it catches up with you)
The zero return is valid when it reflects reality. It stops being valid when: you issued a CFDI in the period (the pre-fill brings them in — declaring zero against issued invoices is the easiest inconsistency for the system to detect and a factory for invitation letters); you collected without invoicing (your bank deposits tell another story); or you've spent years at zero with a visible lifestyle — the "chronic zero" with active credit cards is the textbook tax discrepancy profile. The zero return is an honest snapshot of a slow month, not a fiscal way of life.
The cost of skipping it — and the right way out if you no longer operate
For each return not filed: a fine for the unmet obligation (which multiplies per obligation and per period — three skipped months of ISR+IVA are six fines, not one), demands with their own fines if you don't respond, a negative compliance opinion (goodbye credit, corporate clients and any procedure that requires it), and the final boss: failing to file returns is grounds for restricting your digital seals (17-H Bis CFF) — your invoicing shut off for not filing zeros that took five minutes. Correction is always available (filing late but spontaneously avoids the substantive fines — you only pay what was owed with its accessories, which at zero is… nothing, if you get ahead of the demand). And if the reality is that you're no longer going to operate: don't sentence yourself to filing zeros for life — file the notice of suspension of activities, which legally freezes your periodic obligations until you reactivate. It's the difference between pausing the movie and leaving it running with a fine for every frame.
Carrying unfiled periods — or an 'abandoned' RFC piling up obligations?
Cleaning it up is fast and almost always cheaper than you fear: an inventory of skipped obligations, spontaneous late filing in bulk (before a demand arrives, which changes the price), and the right decision going forward — an adjusted regime, suspension, or an automated calendar so it doesn't happen again. One session and the light turns green.
Frequently asked questions
Is the DIOT also filed as a zero return?
Informational returns follow their own logic: the DIOT (the VAT informative return) is filed when there are transactions with suppliers to report (and certain taxpayers are relieved of filing it — e.g., those who use the pre-filled applications or have facilities based on income level). The right answer depends on your regime: what you must not do is assume symmetry with the monthly tax return. Moderate confidence on specific facilities — verify against the RMF (annual tax regulations) in force for your case.
I filed a zero return and then income for that month came in — what do I do?
You file an AMENDED return for the period, correcting the figures — amended returns exist exactly for this and, filed spontaneously, you only pay the tax with inflation adjustment and late-payment surcharges from the original date. The prior zero return is not an aggravating factor; staying silent after knowing it was wrong is.
Do asimilados a salarios (salary-assimilated earners) or pure salaried employees file zero returns?
Pure salaried employees and asimilados don't file monthly returns (their employer withholds and remits) — their issue is the annual return when it applies. The monthly zero return is a matter for regimes with activity: business, professional, rental, RESICO (simplified regime), legal entities. First step always: know exactly what obligations YOUR RFC has — your tax status certificate (Constancia de Situación Fiscal) lists them.
How many times can I file a zero return before it 'looks bad'?
There's no magic number and no rule that forbids it — there are profiles: a seasonal business or a slow start filing zeros for several months is normal and explainable; an RFC with commercial activity, active seals and years of zeros against bank activity is a risk pattern. If the zeros are going to be long, document the reason (a real pause, a pre-operating stage) or suspend: both are defensible; inertia is not.
Let's talk about your case
The first step is always the same: an honest diagnostic of where you stand. Message us on WhatsApp or call — a reply the same business day.