If you're heading to Mexico on holiday, the bit of paperwork that matters most probably isn't a visa at all — it's the FMM, the Forma Migratoria Multiple, the visitor permit issued to almost every tourist and business traveller at the border.
The good news for many passport holders: Mexico doesn't require a pre-arranged visa from a long list of countries, so most visitors simply receive an FMM on arrival. Even travellers whose passports normally put them on Mexico's 'visa required' list can often skip the visa process if they hold a current US visitor or residency visa — a rule that makes Mexico an easy add-on to an American trip.
How long you can stay is decided at the immigration desk, not by the visa rules. The officer writes a number of days on your permit, capped at 180. If they grant fewer than 180, that shorter limit stands — FMMs cannot be extended or renewed, so you need to leave before the date written on it. Overstaying creates real hassle, so check the figure before you walk away from the booth.
A few other practical points worth knowing. There's no minimum time you must spend outside Mexico before returning on a fresh FMM — in theory you could cross out and back the same day. But border officials do notice serial border-hops and may question why you're repeatedly entering as a visitor, so don't treat the permit as a workaround for living in Mexico. In fact, most people can't convert an FMM into residency: if you decide to stay long-term, you'll usually need to leave the country and apply through a Mexican consulate abroad.
Paper FMMs are also disappearing. Mexico is phasing out the old paper slip in favour of a simple passport stamp, which quietly solves a classic headache for road-trippers who used to drive out of the country with nobody to hand their permit to.
On entry, the immigration officer at the port of entry has final say over who is admitted — this applies whether you hold an FMM or a consulate-issued visa. Mexico can only screen against criminal records that other countries have shared with it, so a past conviction isn't automatically a bar, but if you have any doubts the consensus advice is to check with your nearest Mexican consulate before travelling. Special situations, like getting married in Mexico (same-sex marriages are legal there), have their own rules and paperwork.
For holiday planning, the takeaway is simple: confirm whether your passport needs a visa, remember a valid US visa can cover you, and check the number of days the officer writes on your permit — that's your hard deadline, and it can be anything up to 180 days. With paper permits fading out, the process is getting simpler, but the entry stamp's clock still rules your trip.
