@Paul ***********
you can use monthly income method for your initial in country Non-O visa or the first year extension ONLY if you come from a country whose embassy still issues the affidavit of income from abroad notary letter.
Otherwise you have to have the minimum amount transferred in from abroad to a thai bank account in your name, each month, every month for the previous 12 months
and
you have to be on the same visa/extension when you do the transfers.
What that means is you couldn't start transferring funds in, live here on free stamps, etc for a year then try to apply for the in country Non-O or yearly extension because those previous transfers were done when you were on another entry type and don't count π
initial 90 day Non-O visa/first year extension if you're from a country that doesn't issue the income affidavit here can be by banked money method only