Thailand has a similar tax year like the US, beginning Jan 1 and ending roughly April.
As a US citizen, you need to report your income anywhere you work... Whether you decide if you're going to work under the table is up to you. For Thailand, you should file your taxes with the provincial Dept of Revenue, or pay someone to do it for you if you don't want to deal with it.
If your employer is paying your taxes, ask for a Tax ID # and get it in writing whatever they said to you about your tax situation. Just incase you file later in Thailand and you find out they never paid and YOU owe money.
My employer said they didn't have to file because I didn't make a certain amount. However, when I talked to my Thai lawyer, they said I must file, but it's likely I don't pay anything since my income was low. Additionally, I had to establish my own Tax ID #, which the employer should have done... Which they didn't do.
If I were you, I'd join the Teachers Rights in Thailand group on Facebook, where many people cover this topic... It's something along that name.
Best to consult with a someone experienced with tax laws for Thailand and the US to be safe.
Most importantly, when did you get your first salary from this employer? I think the work permit defense is the employers way of hiding the fact they had you working prior to receiving the work permit, which is illegal.
I never said that it wasn't an option. I just didn't mention Volunteer visa because it's a hit or miss.
Some NGOs that offer volunteer visas have postponed programs due to Covid 19, so they haven't been prepping the documents for volunteer visas for those that are abroad. But if you do your research, you may find an NGO or other organizations that could still help.
Again, it's a hit or a miss.
I know 1-2 schools have helped people get ED Visas from abroad. While Ed Extensions in-country are possible as schools/programs reopen, as the country improves.
Multiple entry is not currently offered - to be honest, I haven't seen anyone enter on multiple entry since Covid. I could be wrong 😐
Special Tourist Visa (STV) can allow stays up to 9months but cannot be converted. This visa is available until Sept 2022, I believe.
Or you can enter on TR visa or exempt and try to convert to an ED/Non-B visa which could allow up to 12 months extension for that visa... depending if you find an employer or a school to attend.