It is indeed for the extension.
Before applying for 1 year extension, you need first to get a 90-day non-immigrant O visa that you can get in any Thai embassy/consulate abroad. Financial requirements will vary according to each consulate (e.g.: "Applicant’s bank statement showing at least THB 400,000 or equivalent in other currencies for the past 2 months", "Applicant's recent bank statement during the past 6 months", ... ).
It is also possible︀ to convert your current visa or visa exemption into a non-immigrant O visa within Thailand.︁
Financial requirement (Bangkok Chaeng Wattana immigration office): need to show 400K THB in a Thai︂ bank account on the day you apply. You need at least 15 remaining days on︃ your visa or visa exempt stamp to apply.
Before applying for 1 year extension, you need first to get a 90-day non-immigrant O visa that you can get in any Thai embassy/consulate abroad. Financial requirements will vary according to each consulate (e.g.: "Applicant’s bank statement showing at least THB 400,000 or equivalent in other currencies for the past 2 months", "Applicant's recent bank statement during the past 6 months", ... ).
It is also possible︀ to convert your current visa or visa exemption into a non-immigrant O visa within Thailand.︁
Financial requirement (Bangkok Chaeng Wattana immigration office): need to show 400K THB in a Thai︂ bank account on the day you apply. You need at least 15 remaining days on︃ your visa or visa exempt stamp to apply.