The balloon date is doing more work than the interest rate on most seller-financed notes right now

The part of this that sellers keep underpricing is the optionality they hand away at signing. A performing buyer who can't refi has all the leverage in an extension conversation, because foreclosing a current borrower is expensive, slow, and in some states requires a deficiency judgment process that makes a deed in lieu look attractive even when the tax hit is brutal.

The one condition worth writing into the note at origination is a rate adjustment trigger at the balloon, something like: if the buyer cannot refinance at prevailing rates, the note converts to a five-year amortizing extension at the then-current prime plus a spread, with no further negotiation required. That converts the workout from a bilateral negotiation into a mechanical outcome the seller already agreed to, which means the buyer's leverage disappears. A real estate attorney in the state where the property sits needs to confirm enforceability before it goes into the note, because some states treat that kind of provision differently in a foreclosure context.

What jurisdiction is the property in, and does the note currently have any language addressing what happens if the buyer cannot refinance by the balloon date?

The structure you are describing is the canonical seller-financing trap, and the reason it is so common is that the balloon term gets negotiated on deal-flow logic rather than capital-markets logic. Five years felt like a long time in the underwriting; it is not long when the rate cycle does not cooperate.

The assumption doing the most work is not the interest rate, as you note, but the refinance availability assumption, and it is compounded by a second one that does not get named as often: that the property's NOI trajectory will be sufficient to satisfy a conventional DSCR test at whatever rate prevails. Both assumptions are entirely external to the seller's control, and neither is typically documented as a condition in the note. That is where the exposure lives.

On the balloon term tradeoff you laid out: a shorter term does force the workout conversation earlier when the seller has more leverage, but the more useful variable is probably not length alone. It is what conditions the note attaches to any extension. A clean extension provision that specifies the rate adjustment mechanism, a floor, caps on how many extensions the buyer can request, and a fee per extension converts what is now an ad hoc negotiation into a scheduled repricing event. The seller still carries the risk, but they price it in advance rather than discovering the cost mid-workout. That provision also signals to the buyer at signing that the extension is not free, which changes behavior earlier.

The deed in lieu question at the end of your scenario is where a tax professional is required, not optional, given the installment sale mechanics and what a property recovery does to the deferred gain structure.

A specific question back: when you have written extension conditions into a note, have you structured the rate adjustment as a spread over a benchmark or as a fixed step-up, and which has held up better when the buyer pushes back on the extension terms?