yearly fee/tax for renting out student rooms?

[mangkut70]

Hello!

Hopefully this is the right place to post this. 

I have a question for people who have experience with renting out student rooms in Thailand (dormitories), specifically regarding taxes on income generated from such rentals or general fees for running a dormitory.

Situation:

My mother-in-law runs a small dormitory. The maximum possible income — based on the number of rooms and the rent per room — is slightly less than 150,000 THB per year. She has no other income.

We built the house several years ago; the family lives downstairs, while students stay upstairs (separate entrance). I never really cared much about this (everything worked like a charm and this setup was sufficient to support the family)

But now I'm wondering because my mother-in-law says she has to pay some kind of tax every year — it's around 10,000 THB — and it seems to be negotiated depending on how many rooms are rented out. I'm not sure which authority is responsible for collecting it.

 

My question:

Is there some kind of special general fee or tax per room when renting out student rooms?

As far as I understand Thai income tax regulations, if you earn less than 150,000 THB per year, there should be no income tax at all.

Am I missing something?