Read the instructions that are part of Form 5305-SEP. Form 5305-SEP is a form that must be kept in the S corp's files, not filed with the IRS.
Also see Chapter 2 of IRS Pub 560: <a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-pdf/p560.pdf">https://www.irs.gov/pub/irs-pdf/p560.pdf</a>
