Overcontribution to prior year SEP of self-employed person

[Guest CarolM]

A self-employed client of mine made a SEP contribution for 1997 in April 1998 based on what we thought was his 1997 self-employment income. In the middle of 1999 (yes, 1999), he received a 1997 K-1 from new partnership which reported a net self-employment loss. This new information has many ramifications; the one I'm most concerned about is that it means that his 1997 SEP contribution was overstated by roughly $4,700. Is there any way to characterize that amount as a 1998 contribution? Or are we forced to comply with the excess contribution/excise tax rules?