My apartment is rent stabilized because my landlord received a 421a tax break. How do I figure out when my rent stabilization ends?. A growing group of New York City tenants benefit from a 1970s-era tax exemption program called 421a, which allows landlords to get tax breaks for up to 30 years in exchange for providing rent-stabilized apartments. But there’s a catch for tenants-rent stabilization only lasts as long as the tax break is in effect.