The information that I am writing here is based on my experience as of March 1, 2016.
I am currently teaching in a government school. I started in March 2015 but I was only taxed in June 2015. I was deducted 875 Baht every month for my TAX and 750 Baht for my health insurance. Another 750 Baht is paid for me by the school as their share, hence a total of 1,500 Baht goes to my health insurance. To sum it up, the amount that is deducted from my salary is 1,625 Baht (875+750) per month.
When I went to the Ministry of Labor to have my work permit renewed, the officer asked for my tax record, which I don't have at that time. It is a requirement for the renewal of work of permit (W.P.5) to present the Phor Ngor Dor 91 form and tax receipt (yellow). Both documents can be acquired from the District Office (Revenue Department).
Prior to going to the revenue office, my school gave me the summary of my tax for the year 2015. The total amount that I paid for 7 months (June 2015 - December 2015) is 875x7= 6,126 Baht.
When I filed the Phor Ngor Dor 91 at the revenue, I was told to get a refund amounting to 5,875 Baht. I don't exactly know how the officer got the computation though it was all written at the back of the form 91. The cheque will be under my name and it will be sent to my school around May to June 2016.
I was surprised to hear that I will get a refund because I never got one before and my school didn't inform me neither. So I asked the officer if I could file for the previous years and she said that I can only refund for the 3 years back. I just need to get the tax record from the school. The paper must contain the total tax paid for the year 2012, 2013, and 2014 respectively.
I told the other foreign teachers in my school to file their Phor Ngor Dor 91 as well. Hurrah! we will all get out refund a few months from now :-)
I hope this information will assure you that indeed, there is a tax return/refund. We just have to file for it. You can either go to the nearest revenue office and file personally or you can ask your Thai friend to help you file online.
For translation purposes of the personal income tax forms, go to this link. http://www.rd.go.th/publish/index_eng.html