When you sublet your apartment, two separate insurance situations exist at the same time. You're the original tenant (the person named on the lease), and you're handing temporary occupancy to a subtenant. Your renters insurance policy covers you as the named insured. It doesn't extend to the person living in your unit while you're gone.
The named insured is the person listed on the policy. Some policies also cover permanent household members who live at the address full-time. A subtenant doesn't qualify as either.







