Trenching needed for upgrade to 220 amp?

I have installed airconditioning and need to get my electrical main panel upgraded to 200 amp. I have had 3 quotes. One tells me I can do it without permit, but to code and don't have to trench (since I have buried cables). Another one tells me I have to trench. Trenching is more expensive than the panel upgrade! Can I go with the no permit but "to code"? I don't plan on ever selling my home....