Individual 401k Contribution Limits. The 2015 Individual 401k contribution limits are $53,000 and $59,000 if age 50 or older (2014 limits are $52,000 and $57,500 if age 50 or older). The annual Individual 401k contribution consists of 2 parts a salary deferral contribution and a profit sharing contribution. Salary Deferral Contribution. 2  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 an Individual 401k (2014 limits are $17,500 or $23,000 if age 50 or older). 3  Profit Sharing Contribution.