Just so happen to have really fresh info from personal experience.
We also did a short trip into Belize a few weeks(Jan -Feb 2012) ago and I asked for specific clear answers when we were at the Subte.Lopez ( Chetumal) ) border crossing into Belize.
If you are going into Belize ( or Guatemala at another crossing)
you DO NOT need to cancel and hand over your TVIP if you will be returning to Mexico within the remaining valid time of that document. It will remain in effect and you can use it until you return to the USA. Then if you do not wish to return with the same vehicle to Mexico within the TVIP remaining valid time it is your responsibility to go to the Banjercito kiosk at the border or the inland highway customs checkpoint and cancel the TVIP.
If you intend to return to Mexico before the permit expires for another short trip you may hang onto it, just ride back into the USA and when you return to Mexico you will be able to show your valid TVIP and breeze through.
If you are not planning on going back into Mexico then you must cancel the TVIP.
Since last year the new process is to charge EVERY Vehicle Owner the security deposit for the vehicle. This REFUNDABLE fee of UP TO $400 USdollar equivalent is deducted from your credit card in addition to the actual cost of the TVIP and even your Tourist Card may be included.
If you fail to exit Mexico and neglect to cancel your TVIP before it expires you will FORFEIT the TVIP security deposit. You have been warned by Banjercito, this is clearly explained in SPANISH on the document you will be given when you obtain your TVIP.
When you are ready to go back to the USA you cancel the TVIP and Banjercito promptly credits the full $400US amount to the same credit card from which it was drawn.
Also on the document it explains that if for some reason the credit card becomes invalid or expires before the return deposit is made it is your responsibility to make contact with Banjercito to notify them of this fact and to provide another account number to which the refund deposit may be made.
When I cancelled my TVIP at Nuevo Laredo the officer gave me the receipt - and - proof- of- cancellation slip which showed the refund. When I returned home I updated my cc account at my bank and it clearly showed that indeed the money was again in my acount as a credit. Great folks at Banjercito, no hanky panky, solid and honesyt, A1 etc etc etc
On a similar note Re : TOURIST CARD
If leaving Mexico for Belize or Guatemala it is ,in 2012 winter , required that you hand over and cancel your tourist card, EVEN IF you know that you will be returning within its remaining valid time. W hen you return to Mexico from Belize o r Guatemala you will then have to fill out anew the document and obtain a replacement Tourist Card. This rule applies only at the south border of Mexico.
If you are leaving Mexico and entering the USA with the intent of returning to Mexico within the remaining time left on your tourist card you may keep it and you will thus save yourself the cost in money and time of getting a new tourist card.
Along the USA side the Tourist CArd is considered valid for MULTIPLE ENTRIES. This was clearly stated to me by the Migracion official behind the counter at Nvo.Laredo two weeks ago.
So, I kept my Tourist Card and cancelled the TVIP for the car. Now I am ready to get on my KLR tomorrow and ride back to Mexico where I will only need to buy a TVIP for the motorcycle.
Hope this clears up any othe r questions.