Agree with ICON.
If you have a work permit then you can basically do whatever tasks are needed to achieve the objectives of the position stated on the work permit (meaning of course a position which is NOT reserved for Thai nationals).
Actually there is a lot of totally wrong / misinterpreted / third hand information floating around about work permits which is why I suggested that the OP go to Thaivisa.com/forum and then search the easy to find threads with full and fully accurate information.
One point I will add, beware of high cost lawyers who will tell you that gaining a work permit is extremely complex and a layman cannot navigate the documents, the procedures, discussions and complex negotiations with the Labor Ministry officials, etc etc. It's all total crap.
Example, the first year I got a work permit to work when I changed jobs to a major consulting company (about 14 years ago) my Thai admin manager was very determined (for status reasons) to use a very high profile international law firm.
They quoted over 100,000Baht to gain the initial permit and 50,000 for annual renewal. I had to basically gag her to stop her proceding.
In fact it was issued using a farang operated professional business agency, and the initial quote for the permit plus the visa was about 8,000Baht . They reduced that fee by about 40% (if my memory is correct) because I have Permanent Resident status therefore a visa was not needed.
The high profile international law firm refused to acknowledge that the visa was not needed and claimed the amount of work / negotiation involved was still the same. I know that the work involved is much less (less because of holding
PR) because my previous employer had established this point very clearly in the past.
If anybody needs the name of the agency I mentioned (Bkk based, lots of advanced English spoken, Thai and farang staff) then please PM me.
If your in the Pattaya area I can share the name of a professional accounting company who can do most of these things with very reasonable costs, and again lots of advanced English spoken.
LATE ADDENDUMThe same company in Pattaya is well recommended for farang who have formed a company in Thailand (
with the required number of Thai shareholders / required shareholding % Thai vs Farang, perhaps for the purpose of buying house and land, or whatever), and therefore need to have an accountant and auditor prepare and lodge annual accounting and audit returns etc, and annual documents to the Thai Companies Office, etc. They are very reliable, very thorough, won't engage in anything 'smelly' and their current annual fee for all of the above is around 13,000Baht which is very reasonable compared to other agencies / law companies etc.