Yes get signed written permission from your boss to state you can work remotely for the company when in Thailand

You will need to file a new TM30 as this will be needed when doing your 90 day report which needs to be done in person when arriving back in Thailand.

@Samuel *******

no you can extend once per entry and therefore stay 360 days total before leaving

Never heard of anyone applying for extension so far. Requirement for extension might be same as initial application.

You CANNOT run a business in Thailand you can only do online work for yourself or have express permission to work online from your employer on a DTV

Did you apply on the Evisa site and check that the country you are actually in allows Evisa, did you upload permission to be in that country such as entry stamps and proof of address. Did you prove that all your work was online with permission to work online from your employer or proof of contracts with customers you actually supply online. If any of your work was to supply customers in Thailand and generated money inside Thailand then it wouldnt be allowable.

Non-o Evisa from London you will be required to show minimum of £18k in your current bank account as final balance on your bank statement on applying

Only if your Embassy certifies income. The US Embassy does not. Best solution is to apply for the initial Non-o in the US , upon arriving in Thailand immediately open a bank account and deposit a minimum of 800k baht ,after its been in there for 2 months apply for your 1 year extension. At the same time deposit a further 65k every month for a minimum of 12 consecutive months prior to applying for your second extension and keep that up forever. Whilst this is in progress your bank account must not drop below 800k for a minimum of 3 months when your first extension is granted and cannot drop below 400k until you apply for your second extension.

Bank statement , updated bank book and letter from bank. All on the date of extension.

Contracts are fine as long as the customer acknowledges work will be online and your customer is not resident in Thailand. Bank requirements vary a lot some want a minimum balance of 500k for 6 months some are happy with your latest statement