Employer contributions appear in a retirement account balance long before they necessarily belong to the employee. Vesting is the rule that determines when ownership actually transfers.
Two pots inside one balance
Contributions made from an employee's own pay are theirs immediately and in full, because the money was already earned before it was diverted into the account.
Employer contributions are treated differently. They are conditional on continued service, and until the condition is met the employee holds only a prospective claim on them.
The account statement usually shows a total balance alongside a vested balance, and the difference between the two is what would be forfeited on leaving immediately.
Schedules come in two shapes
A cliff schedule grants nothing until a threshold of service is reached and then grants the whole amount at once, which creates a sharp step in what an employee owns.
A graded schedule transfers ownership in increments across several years, so an employee leaving midway keeps a proportion rather than nothing at all.
Cliff arrangements produce the largest retention effect immediately before the threshold, since leaving weeks early forfeits everything the employer has contributed.
Vesting is a retention tool
Deferred ownership makes departure costly at specific moments, which is the entire purpose. The contribution functions as compensation that is paid now but earned over time.
Forfeited amounts do not disappear from the plan. They typically return to the employer to offset future contributions or plan expenses, so the cost of turnover is partly recovered.
The arrangement also lets employers advertise a headline contribution rate that overstates what short-tenured staff actually receive.
It changes the arithmetic of moving jobs
An employee weighing an offer should compare vested balances rather than total balances, because the unvested portion may not travel with them.
Where a threshold is close, the value of waiting can be substantial, and it is one of the few negotiating points that has a precise and verifiable figure attached.
Some employers will compensate a new hire for forfeited amounts, but that is a negotiated term rather than a standard practice, and it must be raised before an offer is accepted.
What happens to the account afterwards
Leaving an employer generally does not force a withdrawal. The vested balance can usually remain in the plan, transfer to a new employer's plan, or move to an individual account.
Cashing out instead triggers tax and, below the qualifying age, penalties, while permanently removing the money from the compounding period it was intended for.
Small balances are sometimes moved out automatically by the plan, which is why departing employees should confirm where the money went rather than assuming it stayed put.