You want to know what line 7 means?  YES, PLEASE. 

Just let you know I already have read all articles and links you posted here, If you did not file 8881 before certainly hard to figure it out.

Tax form is 1120-S and should file 8881, but line 7 says : Credit for small employer pension plan startup costs from partnerships and S corporations.

I want to file S-Corp, 1120-S, and line 1 to 5 are about this credit for a  S-Corp, so what is line 7 then?

Who knows what is this and in what case does line 7 have an amount? An example would be greatly perfect.

 Code C on box 16 on K-1 has same amount of code P on box 13 of K-1! Am I right? Is this as nondeductible Code C ( The nondeductible expenses paid or incurred by the corporation aren't deductible on your tax return. Generally, you must decrease the basis of your stock by this amount)

Why this cost is nondeductible on K-1?