Many people saving in 401(k) accounts get a company match from their employer. But that money may not yet belong to them.

Someone may have to remain employed with a company for up to six years to take full control of those matching funds — a longer timeline than is typical for many workers, which may pose an additional financial hit for those laid off in a cooling labor market.

The 401(k) match is often referred to as "free" money: Employees who contribute to their 401(k) plan may get a matching contribution to their account from their employer, up to a certain amount.

About 81% of companies that offer a 401(k) plan offer a match to workers, according to the Plan Sponsor Council of America, a trade group that represents employers with workplace retirement plans.

Depending on the match terms and a worker's earnings, the match money at stake could be worth thousands of dollars per year — and even more when compounded over decades of investing.