Since we only go to pay tax after every year, we will always be a tourist until we have paid tax and got "R.O 22 Certificate of Residence" from the taxoffice. It is not the same as you get from Immigration, that's just a letter. All farang will be consider as tourist until we have this document or have income inside Thailand and pay tax as a local!
You are a tourist until you have 180 days within a tax year, it doesn't matter what kind of visa you have! If we stay more than 180 days in Thailand every year, we are resident and "A TAXABLE PERSON" and have to pay tax, the law say so (..), but we are mostly free, I pay tax every year because I save a lot of tax in Norway if I do! We are not tourists and have a visa for long stay! Tourists can only stay max 179 days, that's why we cannot have too many visa runs. THE TAXABLE PERSON LAW: "Taxpayers are classified into “resident” and “non-resident”. “Resident” means any person residing in Thailand for a period or periods aggregating more than 180 days in any tax (calendar) year. A resident of Thailand is liable to pay tax on income from sources in Thailand as well as on the portion of income from foreign sources that is brought into Thailand. A non-resident is, however, subject to tax only on income from sources in Thailand."