Specific business tax: who pays, at what rate, and how to file

The main groups under section 91/5 of the Revenue Code are commercial banking, finance, securities and pawnshop businesses, life and non-life insurance, and commercial or profit-driven sales of land and buildings. Each group carries its own definitions and exceptions, so being a company or an ordinary shop does not bring you in automatically, and an individual's land sale must be assessed separately. The scope of the business must always be assessed before any duty is concluded.

The ordinary rate is 3 percent of the tax base, plus a local addition of 10 percent of that tax, giving a combined burden of roughly 3.3 percent of the base. This is the general-sale rate only; any temporary reduction or special case must be checked against the announcements in force on the transfer date.

The starting base is the higher of the sale price or the official assessed value, and obligations the buyer takes over from the seller, such as an assumed mortgage, may be added. Setting a contract price below the assessed value therefore does not shrink the base to the agreed figure.

An operator in scope must file the SBT registration application within 30 days from the day the business commences. This registration is a separate duty from VAT registration, so already holding a VAT number does not replace it.

As a rule, form PT.40 must be filed and the tax paid by the 15th of the month following the month the income arose, and a return is still due in months with no income. For in-scope sales of immovable property, the tax is instead assessed and paid at the land office on the transfer registration date, not through a monthly return.

Where the computed tax for a month is below 100 baht, the law does not collect that month's tax, but relief from payment is not relief from filing: the PT.40 return is still due every month. The threshold compares against the computed tax, not against revenue.

Income from an activity subject to SBT is generally not also charged VAT on the same receipt, but one operator can run an SBT activity and a VAT activity side by side — for example a company with both a finance business and a rental business. Each stream must be separated and filed under its own tax.

The law exempts certain activities and cases, such as disposals of land and buildings not undertaken as a trade or for gain, where the prescribed conditions are met, together with exemptions under specific legislation. Each exemption carries its own sub-conditions, so qualifying must be proven issue by issue rather than assumed from the business label, and supporting evidence should be kept for inspection.