He normally builds houses for other customers.  They pay for the materials and he doesn't have a lot of expenses to claim on the construction business with the exception of equipment & tool depreciation and vehicle expense.  The house was certainly not in inventory.   He has a rental house and the rental house had two lots.  Since Covid had slowed his business down and the housing market has gone crazy he decided to build.  The house was built in 4 months, and he knew his sub contractor was going to purchase it within a month of when he started building.  The sale would not push him over the SS limit for self-employment since he has a large farm that normally keeps his taxable social security limit down.  Although the farm did make a considerable profit this year.  The installment sale would lower the amount in taxes due this year and he will most likely have much less income in the following years.   

I appreciate you giving me something to think about.