Accepting Cash to Discount a Note

We have a resident who bought their home on contract about 15 months ago. This resident has approached me about paying off their note with the “big” tax return money they anticipate, and suggested that I discount the note if they pay it in full. Their note is 12% interest annually, payable for the next 9 years, monthly at $401/mo (i.e., $5,000/yr) with a current balance of about $26,000. They also pay monthly space rent in addition to the note payment. What are your thoughts in discounting this note? It seems like there is not a lot of incentive to discount the note for early payoff, except for the issue of the possibility of this resident defaulting in the future and getting a home back that will need rehab before finding a new buyer. The resident pays their monthly account yet also always are late and incur late fees on a regular basis. Ideas?