I've said this before too.......
One year we crossed into Mexico at Nogales.
We returned to the US at Laredo/Columia that year.
The guy where we turn in the vehicle permits said we did not need to turn in the FMM - so we didn't. I think this was a communications/language problem and we misunderstood each other.
The next year we went to cross at Columus,NM/Palomas and when we did our paperwork the guy knew right away we did not turn our papers in the previous year - so I am going to guess they know somehow - and they do keep records - and the records are in the system throughout the system no matter where you cross in either direction. The guy told us it was a $5 a day fine for every day we went over the permit period - I do think he was joking - maybe. I do not think it is anything to worry about - but then again???
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