A carried note is only as good as the collateral behind it, and that reorders every other question
There is a line attorneys use with owners about to carry paper, and it deserves more attention than it gets. The note is only as good as the collateral. The plain version is that if the buyer goes quiet, the seller stops collecting payments and starts managing a foreclosure, and what comes back at the end is only worth what it was worth when the note was written. That makes the rate and the term, and even the down payment, close to secondary questions. The collateral question comes first. Take a fourplex in Tacoma where the owner is open to carrying at 7% over 15 years with 12% down. The buyer will run the income numbers all day. The seller's exercise is different. Go look at what the building would actually bring at a distressed sale in that zip code, then compare the note balance at year three against that realistic distressed price. If the gap is not comfortable, the seller is the one who finds out the hard way, and that is worth knowing before anyone signs.