Another question about traveling

I currently with at home and I don't pay any rent at all.

If I accept a travel assignment, and the agency pays for my apartment/utilities/weekly allowance, and the agency claims that NONE of this will need to be reported at the end of the year so long as I can prove residence elsewhere. will I have to show proof at the end of the year that I have been payinng rent elsewhere?

I am so confused about all of this.