I am partner in a C corporation, with less than 10 employees. I have a non-prototype 401K that I set up allowing me to contribute standard amts, plus any additional employer contributions up to the annual limits. This does not appear on my W2 since it is different from our employee 401k that we offer our employees (not the partners/owners). Can you verify where I should be reporting this non-prototype 401k contribution in turbotax.
It depends. If you made employee contributions to the non-prototype 401(k), these are typically pre-tax and should already be reflected in your taxable income. Since these contributions don't appear on your W-2, you don't need to report them separately in TurboTax.
Employer contributions to your non-prototype 401(k) are not included in your taxable income. However, they should be reported on the corporation's tax return as a business expense. As a partner, you wouldn't report these contributions on your personal tax return.
Maybe I'm not understanding the circumstances, but with respect to this C corp, there can be only one 401(k) plan that covers all of the eligible employees, including yourself. Your own elective deferrals from wages you receive from this C corp must be made to the same 401(k) plan as the one the covers the rest of the employees and are required to be reported on your W-2. Perhaps this "non-prototype 401(k)" that you mention is actually not a 401(k).