Dated before extension letters were widely in use. This thread started April 27, 2017.
We flew on an extension letter to Cancun last year as I’ve documented in this thread. There was zero questioning from the Mexican border guard.
I’m going to guess that Mexican embassy policy has about as much relevance to Mexican border guard policy as U.S. embassy policy has to U.S. CBP policy.
With extension letters the difficulty is, in order of most difficult to least difficult:
* the airlines and cruise lines. Some are more difficult than others. Some like Delta flat out refuse to transport an LPR with an extension letter to Mexico. Others need convincing. Of course some airlines have no problems with extension letters.
* CBP. I saw a report in 2022 or 2023 of a CBP officer at a land port of entry having never seen one and having no idea what it was. Or CBP sends the LPR to secondary. Of course some CBP officers have no problems with extension letters. Some don’t even bother to look at them.
* border guards at countries that grant a visa waiver to U.S. LPRs. Mexico isn’t one of them in my experience or AFAICT the experiences of LPRs who have posted their experiences in 2020, 2022 and 2023. I’ve yet to see a single case since 2020 of a Mexico denying entry to holders of expired green card and non expired extension letters.
The above member flew even after another member insisted a visa was required.
My wife’s experience: