Read about this and wondering if it's legal in Thailand and if you need to be registered with some authority or have a business structure...

Suppose someone wants to buy a condo in Thailand but they can't get a mortgage. Can an farang step in and lend the money and get interest on the loan? Would need to be set up so that the lender held onto the title deeds until payment was complete.

For example, a farang from USA wants to buy a 2m baht condo but only has 1m baht. Another farang lends him 1m baht at 10% annual interest and full payment due in 5-10 years.

Yes, you register it at the land office. The land office has a separate mortgage page with all of the information on it. This is stapled to the chinote. The lender's name is on the back of the chinote as the mortgage holder. The lender holds the chinote. The land office has an identical copy. The lender, land office and borrower all have a mortgage sheet.

If you would like info on the TT3, foreign exchange letter required, message me. If the buyer is buying a 2nd hand condo, then he will also need a maintenance letter from the condo, which the seller will provide. WIthout it, the condo cannot be transferred.