Proprietary Lease
The lease a co-op corporation gives each shareholder that grants the right to occupy a specific apartment. Paired with the stock certificate, it's what you actually get when you "buy" a co-op.
Last updated: October 3, 2026Buying a co-op doesn’t get you a deed. The co-op corporation owns the building; you buy shares in that corporation, and the corporation hands you two things at closing: a stock certificate showing how many shares you hold, and a proprietary lease tying those shares to a specific apartment. Technically that makes every co-op owner a tenant of a corporation they partly own, which is about as New York as property law gets. In practice the lease lets you occupy the unit essentially indefinitely, and the shares and lease can be sold together like any other apartment.
The proprietary lease is the rulebook for that tenancy, including which repairs are yours and which belong to the apartment corporation. Your monthly maintenance is the rent side of the arrangement, and it’s set by your share count (see the example below). New York’s offering-plan regulations require a co-op conversion plan to disclose that each shareholder will enter into a proprietary lease, and the lease’s text, which is binding on the corporation, has to be consistent with what the plan discloses. If you want to know what a building can make you do (or stop you from doing), read the lease and the bylaws, not the listing.
It also matters to your lender. A co-op loan generally can’t be secured by a deed, since there isn’t one, so the bank instead takes your stock certificate and proprietary lease as collateral. That’s one reason co-op financing works best with a lender who already knows the NYC co-op process.
Worked example
Maintenance is allocated in proportion to shares, so the share count on your certificate drives your monthly bill. Say a hypothetical building needs $1,440,000 a year from shareholders and has 20,000 shares outstanding: that’s $72 per share per year. An apartment with 200 shares pays $14,400 a year, or $1,200 a month; a 500-share penthouse in the same building pays $36,000 a year, or $3,000 a month. Plug your own maintenance figure into the Co-op Calculator, or see co-op vs condo costs for how this compares with owning a condo outright.