A proprietary lease in co-op housing is the contract between you and the cooperative corporation that owns the building, giving you the exclusive right to occupy a specific apartment in exchange for the shares you hold in that corporation. It is not a deed, and co-op ownership is not real property ownership. Your right to live in the unit flows entirely from this one document, which also sets what you pay each month, what you can and cannot do with the apartment, and the conditions under which you could lose it.
How the Lease Fits With Your Shares and the Other Documents
When you buy into a co-op, you purchase shares in a corporation that owns the entire building and the land under it. The number of shares tied to your unit generally reflects its size, location, or original value. In return for those shares, the corporation issues you a proprietary lease covering a designated apartment. Lose the lease and your shares can be canceled; lose the shares and the lease goes with them. The two travel together.
Most proprietary leases run for long terms, often 99 years, and they transfer or renew automatically when shares change hands. In practice, shareholders hold their units indefinitely as long as they comply with the lease.
The lease sits inside a stack of governing documents, and it helps to know the order. The offering plan (sometimes called the prospectus or “black book”) is the original document that created the co-op and set out its financial structure. The bylaws govern how the corporation runs: board elections, voting, corporate decisions. The proprietary lease is the binding agreement between the corporation and each individual shareholder. Below all of these sit the house rules, day-to-day conduct rules the board can usually amend on its own, covering things like move-in procedures, noise hours, and laundry room schedules. Amending the proprietary lease or bylaws generally takes a supermajority of shareholders. When a house rule conflicts with the lease or bylaws, the higher document controls.
What the Lease Gives You and What It Demands
The lease grants you exclusive occupancy of your apartment and use of common areas such as lobbies, hallways, and shared amenities. Shareholders also typically have voting rights in corporate matters, including electing board members and approving changes to the governing documents.
In return, the lease loads several financial and practical obligations onto you.
Monthly Maintenance and Special Assessments
Your monthly maintenance covers your proportionate share of the building’s operating costs: property taxes on the building, interest on any underlying building mortgage, insurance, common-area utilities, staff salaries, and reserve-fund contributions. The board sets the amount annually and can raise it year to year.
On top of that, the board can impose special assessments for unexpected expenses or major capital projects such as a new roof, elevator modernization, or facade repairs. These one-time charges can be substantial, and shareholders generally cannot refuse to pay. Courts apply the business judgment rule to board assessment decisions, so a shareholder challenging one has to show bad faith or a breach of fiduciary duty to have it overturned.
Who Fixes What
The lease draws a line between what the corporation maintains and what falls on you. The building is typically responsible for structural elements and anything behind the walls: the roof, exterior walls, shared plumbing risers, mechanical systems. You handle most things inside the apartment, including appliances, interior walls, ceilings, floors, and electrical and heating fixtures. The precise line varies by co-op, so your specific lease language is what matters when a pipe bursts or a window fails. Disputes over that line are among the most common shareholder-board conflicts.
Selling, Subletting, and Board Approval
The lease and bylaws give the board gatekeeping power over who lives in the building, both as owners and as subtenants.
A buyer must be approved before a sale can close. Boards typically require a detailed application with financial statements, tax returns, bank statements, employment verification, and personal references, often followed by an in-person interview. Board discretion is broad but not unlimited. The Fair Housing Act makes it unlawful to refuse to sell or rent a dwelling based on race, color, religion, sex, familial status, national origin, or disability, and co-op boards are not exempt.1Office of the Law Revision Counsel. 42 USC 3604 – Discrimination in the Sale or Rental of Housing Many state and local fair housing laws add protected categories beyond the federal list.
Many co-ops also charge a transfer fee when shares change hands, commonly called a flip tax even though it is not a government tax. Flip taxes typically range from 1 to 3 percent of the sale price and are usually paid by the seller, with the authority for the fee set out in the offering plan, lease, bylaws, or a properly adopted amendment.
Subletting restrictions catch many buyers off guard. Nearly all co-ops require board approval to sublet, and many boards can grant or deny requests for any reason. Common restrictions include a minimum residency period before subletting is allowed (two years is typical), caps on total subletting time (such as two out of every five years), and sublet fees payable to the co-op. Some buildings prohibit subletting outright. If there is any chance you will need to sublet within a few years of buying, read the subletting provisions before you sign anything.
How the Lease Can Be Terminated
The corporation’s power to terminate the proprietary lease is what makes co-op living meaningfully different from condo ownership. Termination means you lose the right to live in the unit, and your shares can be auctioned to repay what you owe the co-op. Anything left over goes to you, but shareholders in default rarely come out ahead.
The most common path to termination is non-payment of maintenance. The process generally starts with a formal demand, followed by a notice to cure giving you a window to pay. If you do not, the corporation issues a notice to terminate the lease and can either bring an action in housing court for possession or, depending on the governing documents, proceed with a non-judicial foreclosure and auction of your shares.
Boards can also seek termination for persistent, serious misconduct, such as chronic harassment of neighbors or staff, repeated lease violations after warnings, or conduct that threatens other residents’ safety. The board has to act in good faith, follow the procedures in the lease (typically written notices and an opportunity for the shareholder to be heard), and show a legitimate corporate purpose. Courts apply the business judgment rule and generally will not second-guess the decision when those safeguards are in place.
Tax Deductions for Shareholders
One financial benefit of co-op ownership comes through the lease relationship. Under 26 U.S.C. ยง 216, shareholders can deduct their proportionate share of two categories of expenses the corporation pays: real estate taxes on the building and land, and interest on the corporation’s mortgage debt used to acquire, construct, or maintain the property.2Office of the Law Revision Counsel. 26 USC 216 – Deduction of Taxes, Interest, and Business Depreciation by Cooperative Housing Corporation Tenant-Stockholder
Your proportionate share is normally based on the percentage of total outstanding stock you own. The corporation can elect an alternative method that allocates deductions based on the cost attributable to each specific unit, including that unit’s share of common areas. If it uses that alternative method, it must give each shareholder a written statement by January 31 of the following year showing the taxes and interest allocated to them.2Office of the Law Revision Counsel. 26 USC 216 – Deduction of Taxes, Interest, and Business Depreciation by Cooperative Housing Corporation Tenant-Stockholder
For shareholders to qualify, the corporation itself has to meet one of three tests: at least 80 percent of its gross income from shareholder payments, at least 80 percent of the building’s square footage used for residential purposes, or at least 90 percent of expenditures going toward maintaining the property for shareholders. Most residential co-ops easily satisfy one of these. If you also have a share loan to buy your shares, the interest on that personal loan may be deductible as mortgage interest, subject to the usual limits.
The Underlying Mortgage Risk the Lease Doesn’t Protect You From
One risk is worth flagging because the proprietary lease does nothing to shield you from it. Most cooperative corporations carry a blanket mortgage on the entire property, and your monthly maintenance covers your share of the interest. If the corporation defaults on that mortgage, the lender can foreclose on the whole building, and every shareholder’s investment can be wiped out regardless of whether individual shareholders kept up with their own maintenance. That shared exposure is why boards scrutinize applicants’ finances closely, and why anyone buying into a co-op should review the corporation’s financial statements, the terms of the underlying mortgage, and the reserve fund before closing.