individual 401(k) Plan - compensation and deferral question

[wsp]

Can an owner of an S-Corp reclassify his compensation post 12-31? And in doing so make deferrals into his individual 401(k) plan at any time up until 4/15? Everything I have read, including earlier message boards say yes this is allowable because the individual is not subject to the ERISA standards of section 21510.3-102(B)(1).

So, then if there is a reclassification and thus an increase in the Self-Employment portion of the SS tax then it would typically be done after the submission of the 945's in February thereby making a revision of those forms necessary and a penalty for late filing.

Are there any other drawbacks or pieces that I am missing here?