Cancun self
 

I have a trip ending with a dh from Cancun. Anyone deviated and know what taxes or fees are from Cancun? Thanks

I assume you must be considering a JS on some other carrier, otherwise if you deviate DH on DL to another city it's still a company ticket.

You can get an idea of the fee's by just booking a non rev seat on Travelnet one way and seeing what it charges you to return. I have found though that the "taxes and fees" out of foreign destinations don't seem to be as standardized as you would think across carriers. A couple of times I had paid (supposedly taxes/fees) for JS travel on OAL from international carrier but didn't get on and paid a separate fee that was quite different on the next carrier.

DH to CUN?
 

If I deviate on DL metal to CUN, do I have to clear customs, then go back through security to operate the outbound flight? What if I stay on the originally scheduled DH?

Assuming CUN and YYZ use the same procedures then yes you will. I had to do this on a 52 min turn about a year and a half ago. YYZ red coat said unless you operate it in you have to clear customs because you were listed as a pax on the gendec.