Schedule C Employer Contribution Limit

For an employer who files a Schedule C and has a few W-2 employees. Is the plan deductibility limit for employer contributions (employer's net Schedule C + w-2) * .25? 

Does anyone have any information on this? 

Assuming you are talking about a DC plan, it is a circular calc; it boils down roughly to 25% of (covered) W-2 comp plus (roughly*) 20% of Schedule C.

*There is an adjustment for 1/2 of SS taxes; after that it is 20%.

Also note the Schedule C should reflect the employer contributions for employees, so if you are a TPA and are given the raw Schedule C by the accountant, you have to adjust for that as well.

The employer limit for the totality of the plan would be: Total employer contribution = .20(Net Schedule C - 1/2 SS taxes) + .25 (Total W-2 Wages) 

Ex: Maximum employer limit = .20(150,000 - 11,475) + .25(100,000) = $52,705

Is this the correct formula for a self-employed Schedule C filer? 

https://www.irs.gov/retirement-plans/self-employed-individuals-calculating-your-own-retirement-plan-contribution-and-deduction