In 2015, 100% of W-2 earnings up to the maximum of $18,000 or $24,000 if age 50 or older can be contributed to a Self Employed 401k (2014 limits are $17,500 and $23,000 if age 50 or older). Profit Sharing Contribution :A profit sharing contribution up to 25% of W-2 earnings can be contributed into a Self Employed 401k.n 2015, 100% of W-2 earnings up to the maximum of $18,000 or $24,000 if age 50 or older can be contributed to a Self Employed 401k (2014 limits are $17,500 and $23,000 if age 50 or older). Profit Sharing Contribution :