Sep contribution is reported by SEP administrator based on the year in which  it is made, Not the year that it applies to... Therefore in the past the IRS had problems correctly matching the sep contribution to the return... A few years ago I had a client where they screwed it up and tried to bill them a large amount for a so-called disallowed SEP contribution over the maximum... I had to send a letter with all of the documentation from the client and the SEP administrator and then they corrected their letter... so make sure you save all the documentation, like the cancelled check(s) and so forth .... for what it is worth...just my opinion...