The maximum contribution to a 401(k) refers to the maximum amount of money an individual can contribute to a 401(k) plan every year. This limit is set annually by the IRS and as of 2015, it is set at a maximum value of $18,000.
Employees who are over 50 years old are also able to contribute up to $6,000 in catch-up contributions, making the maximum employee contribution limit $24,000 for 2015. The IRS classifies contributions to 401(k) plans as elective salary deferrals. In 2013 and 2014, the maximum contribution limit for a 401(k) plan was set at $23,000, of which $17,500 was the elective salary deferral limit.