Tax guy Bill, yes you are right. The k1 already reports the shareholders share of n the installment sale. I got confused bc the k1. In box 17 code N details all the shareholder’s portion of the instalment sale and I mistakenly assumed, this is my first sub s installment sale experience, that meant the shareholder was required to repot his share of the sale on his own 6252. Now I realize the line 17 code  N info is for reporting code section 453A(c), not for retrofitting the 6252 info. Thanks for your input.