I am currently teaching at a university in Thailand with a Non-Imm B visa and work permit.  The visa expires on Sept. 30, 2021, but should be extended to Sept., 2022.  I plan to visit California in the U.S. this May and return to Thailand in July.  My question is how many days should my COVID-19 insurance package cover to obtain the COE from the Thai Embassy - 90 days (from July to September), or will I have to spring for a full year's coverage?  Also, beyond the required passport and work permit pages, flight ticket, ASQ reservation, and negative COVID-19 test, are there any other recommended documents I need to submit, such as a letter from the university or special permission from the Ministry of Education?  If it makes any difference, I have been a lecturer at this university for almost 20 years.  Thanks for any information you can provide.  

You will need the covid 19 insurance valid to the day your extension of stay and re-entry permit expires in September.

No need for anything from the university or the ministry of education.

Just copies of your passport pages and work permit. And of course ASQ hotel and flight reservation.

There will probably be changes before you return in July. The quarantine may be much shorter.

If possible I suggest you get vaccinated while in the states that at this time would reduce the quarantine to 7 days. 

Thank you so much.