Mexico let over 40 million international tourists in during a normal pre-pandemic year, and most of them never got asked about a return flight at all. Some did. That inconsistency is the whole story here. A dummy ticket, also called an onward ticket, is a real PNR booked for visa or border-check purposes without paying for the flight, and whether you need one for Mexico depends less on the law and more on who's standing at the desk that day.

Does Mexico actually require an onward ticket at the airport?

There's no single federal rule that says every tourist must show one. What you will need is a completed FMM tourist card, which the airline or a kiosk hands out before immigration. On top of that, the U.S. State Department's country information page for Mexico notes that travellers can be asked to show proof of sufficient funds and a return or onward ticket, and it's the officer's call in the moment, not a fixed checklist posted at the counter.

What if I'm crossing by land instead of flying in?

This is where it gets less predictable, not more. At a land crossing, there's no airline gate-checking your documents before you reach immigration, so the ticket question, if it comes up at all, comes from the officer directly. If you're planning a longer overland route through Central America, the same logic applies at land border crossings generally: no ticket to check because there's no flight, but you can still be asked how you plan to leave the country before your permitted stay runs out.

Does my FMM tourist card cover this, or do I need something else?

The FMM covers your entry paperwork and tracks your permitted stay. It doesn't replace proof of onward travel if an officer decides to ask for it. Think of them as two different questions: the FMM answers "are you allowed in," and the onward ticket answers "do you have a credible way out." You can have a perfectly valid FMM and still get asked the second question.

What actually happens if I don't have one and get asked?

Usually it's just a conversation: where are you going next, how long are you staying, do you have a way out. Officers aren't hunting for a specific document format. They're checking that your story holds together. If you can't answer clearly and have nothing to point to, expect a longer chat at the desk, not an automatic ban from entry. It rarely escalates further than that at a first-time tourist entry.

Does a return ticket home work the same as a separate onward one?

Yes, functionally. What matters is that the ticket is real, dated within your permitted stay, and matches your passport name. Whether it takes you home or on to your next country doesn't change what the officer is actually checking for. If you're weighing which one makes more sense for your route, this rundown of onward versus return tickets breaks down when each one fits better.

Can I just book something cheap and cancel it after?

That's the generator trap. A ticket that gets cancelled the moment you're waved through still shows as cancelled if anyone searches it again later, and a pattern of always-cancelled onward bookings is worse than having none the first time. If you want a ticket that actually holds up if it's checked twice, a real one that stays ticketed through your travel dates is the only version that does that reliably.

Does it matter if I'm staying for months, not weeks?

It changes the conversation more than the paperwork. Tourist entries under the FMM are meant for shorter visits, and someone showing up with a one-way ticket and no plan for months on end is exactly the profile that draws the "how do you intend to leave" question. It doesn't mean long stays are impossible. It just means the onward-ticket question gets asked more often the longer and vaguer your plans sound at the desk.

Air vs land entry: what to actually have ready

Flying into Mexico Crossing by land
Who might ask Airline at check-in, then immigration Immigration only
FMM tourist card Issued before you reach the desk Issued at the crossing itself
Onward ticket relevance Possible at either point Only if immigration asks directly
Best backup A real, ticketed onward or return flight A clear, honest answer about your route out

None of this means Mexico is strict. It means the check is inconsistent enough that "I'll just wing it" isn't a great plan, and "I have a real answer either way" is.

Sort a proper onward ticket with My Dummy Ticket before you fly, so whichever officer asks gets the same solid answer.