I just recently picked up a defined benefit pension plan that is sponsored by a sole proprietor.

Upon inspection of the records, I have discovered that some of the checks written to fund the plan were not written from the business account, but rather from the sponsor's personal checking account and from the personal checking account of his wife.

If the plan sponsor were a corporation, I know that there would be a problem, but due to the manner in which a sole prop takes the deduction for contributions to a qualified plan, is this a problem? Any citations for me to look at?

I don't see any problem with the deduction coming from his personal account, as the sole proprietor is the individual.

I'm not certain about the contribution coming from the spouse. My guess is that this also would not be a problem in a community property state, and perhaps not a problem even in a non-community property state if they file a joint return--but that part is just a guess.