I've never dealt with a plan that hadn't contributed their Required Minimum by 9/15.

Is this true (basic example):

Required Minimum = 100
Contribution made on 9/16 = 100
Funding deficiency for 2007 = 100
Tax deductible contribution for 2007 = 0

if this is true, what is the reg for this?

Andrew

IIRC, a sole proprietor who is on extension to 10/15 can still have a deductible contribution for 2007.

Is it possible the contribution was made on 9/15 but not received by the financial institution until 9/16?

it's a pc

and no, the contribution was actually made today.

As to the deduction, see IRC Section 404(a)(6).