It depends. Usually if you leave a job and have any unused vacation left over, they have to pay you for that time. There’s a catch though, they do not have to let you carry over your vacation from year to year (use it or lose it), and/ or they can set a cap of how much vacation you can have accrued. In the latter, you can either lose any vacation over that cap, or some employers might be “kind” and let you convert excess vacation into sick time. Sick time does not have to be paid out when you quit.

My employer, for example, allows us to accrue up to 240 hours of vacation time; anything above 240 gets converted to sick time. We can accrue as much sick time as we want. So long as we remain employed, it never expires. We can also apply our sick time toward our retirement.

At my company, it’s not unheard of for employees to stick around for 20+ years before retiring. If you bank all of your sick time, you can apply toward your retirement date and retire up to three years early. And, a lot of people when they retire will have enough vacation available that they can take a month off before officially retiring; and the company does not stop them.

Also it should be noted, I work in the public sector and am considered a state employee. So that helps.