Account owners under the age of 50 can contribute up to $18,000 to their traditional 401(k) accounts, as of 2015. Owners of SIMPLE 401(k) plans can contribute up to $12,500, according to the Internal Revenue Service. The IRS sets these limits, although individual plans can set lower limits.
Traditional account owners who are 50 and older can contribute an additional $6,000 if their plans allow catch-up contributions, for a total of $24,000, the IRS notes. If plans don’t permit catch-up contributions, employees still can contribute up to $24,000 total if they have multiple employers and multiple accounts. In that instance, the maximum contribution to any one account is $18,000.