You don’t need to visit the immigration before you’ll apply for 30 days extension if want. Just be sure you’ve got a TM.30 address registration. This is the hotel or landlords responsibility.
Feedbacks are that there’s no official limit by land borders anymore, yet there’s no official statement regarding this. You’ve only done one border run and stayed 90 (or 120 days in total) and should be fine with another border bounce and a new 60 days visa exemption.
If you’re on the old 30 days visa exemption (before July 15th) you only can extend with additional 30 days at 1900 baht at your local immigration as explained. You’ll need to do a border run to get the new 60 days visa exemption.
One guy I know managed to do things this way, but he went back to Australia, just continued to transfer 65K a month and applied for a new 90 days Non O at home with his income and they accepted all his transfers (18 months consecutive) for his first year extension of stay. So in the end he managed to go around the 800K baht requirements himself.
I know people have done things this way previously, but personally I feel that it might be a bit between you an the IO your standing in front of if they will accept transfers for your initial 90 days Non O as well. You might need to apply for a new 90 days Non O at home and show your consecutive transfers for your extension of stay. This is at least my personal view and you could put it as a note in your reminder for this as well.😉
For your first one year extension the 800K baht has to be in your bank account two months prior to the application and three months AFTER the extension of stay is issued AND it can never drop below 400K baht at any point.
If you want to apply for a new extension of stay you have to bring it back in 800K baht again two months before your next extension.
If you want to switch to the income method for your second extension of stay, you’ll first need to prove twelve months consecutive transfers of min 65K baht over sea, and the 800K baht is again free to use.