I've searched the group but am still not sure what the financial requirements are for Non-Ed visa. Is it 300 or 500K for 30 or 90 days before applying for a one year extension? And what is the window in which one should apply for the extension (meaning days before the extension deadline)? Thanks.
TLDR : Answer Summary
The financial requirements for a Non-Ed visa extension are not strictly defined, as there are no financial stipulations for the Extension of Stay based on study in Thailand. However, if you are on a Non Immigrant O Visa and extending as a family member of a student, you might need to show 500,000 THB in a Thai bank account for a minimum of 3 months prior to applying. It is advisable to apply for an extension between 30 days before your current visa expires and the last day of permitted stay.