A tm30 most likely although might not be the case for a tourist visa but definitely check with someone on that as immigration love stinging farang with their 1600 baht penalties that are supposed to be the landlords fine
They won't question you until you've done this several times. You never get questioned at immigration when doing a 30 day extension. Just make sure you have a tm30. They'll scam you for 1600 baht if you don't have one. They say it's a landlords responsibility to submit for a tm30 yet they fine us on the spot telling us to be reimbursed by the landlord. A genuine immigration would mail the fine to the landlord. It's a sneaky horrible scam this one but of course easily avoided as long as you make sure it's done. Good luck