If I built a shed for storage to warehouse books related to my S-Corp (as a book publisher), how do I enter it as an expense for my self employed income?

[Mike9241]

you should consult a tax pro.  if the S-corp made the income, a return for it had to be filed by 3/15/2021. the penalty for late filing is $200/month/shareholder.  if you have an S-corp as your business you don't have self-employment income. with a corporation you are supposed to take a salary (w-2).  failure to do so can result in penalties besides the late filing penalty.  you are likely to misfile if you don't understand the tax laws involved and thus possibly incur other penalties. 

[Carl]

It's not an expense for your self-employed income reported on SCH C. It's an expense for the S-Corp reported on the 1120-S Corporate Tax Return.