You build up sick leave over time at your job, so it makes sense that your company should pay you for unused sick leave when you quit. However, that's not usually the case. Federal law does not require employers to provide paid sick leave – much less to pay you for it if you resign without using it. Many states have laws that require employers to pay departing employees for unused vacation time, but it's up to individual companies to decide whether to pay for unused sick time.
Negotiate payment for unused sick leave when you sign your initial employment contract. It might seem odd to be negotiating the terms of your resignation when you haven't even started working yet, but it helps the company predict its financial liability in the event you do quit. If your company offers vacation time, it's likely the contract already states you will get paid for unused vacation time if you resign. Adding sick leave to the verbiage isn't a difficult change, if your employer is willing.
Use Your Sick Leave
If your company is unwilling to buy out your unused sick time, use your sick leave before turning in your resignation notice. Check your company's employee handbook to determine whether you can take the leave in consecutive days. Some employers only pay consecutive sick leave days if you have a doctor's note.
Read your employer's leave policy to determine if sick leave is separate from vacation time or whether it's all lumped together as paid time off. If your company offers paid time off rather than separate vacation and sick time, the paid time off is usually treated like vacation time. If your company policy or state law says your employer will pay you for unused vacation time, it must pay you for all unused leave time, even if some of those days were meant to be used as sick time.
Many employers won't allow you to use paid sick leave after turning in your notice; they expect you to work your notice to wrap up loose ends and train a replacement.