The Grand Prospect Is Leasing on the Old Hall Site. A 421-a Deadline May Reset Its Affordable Rents
November 5, 2026
November 5, 2026
On Prospect Avenue near Fifth Avenue, the gilded 1902 banquet hall is gone. In its place stands a long, low building of brown brick and dark metal panels with floor-to-ceiling reflective glass. Brownstoner described it as "modern and dark with no embellishment." Hill West Architects designed it, and New York YIMBY reports that Angelo and George Rigas developed it. It goes by The Grand Prospect, and its own website says "Now leasing" and lists 150 residences.
For renters comparing Park Slope and South Slope buildings, one number spread quickly. A two-bedroom "affordable" unit would rent for $4,738. That figure is real. But the tax-law deadline this building is up against may also require apartments priced at a fraction of it.
Brownstoner reported on October 6, 2026 that the project uses the now-expired 421-a tax break. It said the building must set aside 20 to 30 percent of its units for households earning around 130 percent of Area Median Income, the band the city calls "middle income." At that level, Brownstoner wrote, a three-person household could earn up to $198,510 a year and a two-bedroom would rent for $4,738.
HPD's 2026 AMI table lists $198,510 as the 130 percent limit for three people. HPD's rent chart, which is still labeled 2025, lists $4,738 as the 130 percent maximum for a two-bedroom, $3,948 for a one-bedroom and $5,476 for a three-bedroom.
The 130 percent figure describes one of several affordability structures in 421-a. The calendar is what decides which of those structures a building like this one can still use.
The current version of the program, 421-a(16), also called Affordable New York, covers projects that started construction between January 1, 2016 and June 15, 2022. Under the program terms HPD publishes, those projects had to be completed on or before June 15, 2026.
At 263 Prospect Avenue, work continued well past that date. In early October, Brownstoner found the site still mostly behind a green construction fence, with workers doing hardscaping and a playground and driveway going in along 16th Street. On November 1, New York YIMBY reported that landscaping and new sidewalks were in place and crews were finishing the interiors and front entrance.
In 2024, state lawmakers moved the completion deadline to June 15, 2031, with conditions attached. HPD says the extension covers projects that filed a Letter of Intent by September 12, 2024 and selected Affordability Option A, B, D, E or F. The Mayor's Office announcement from June 2024 puts it plainly: for projects in the extension, the change "removed the controversial Options C and G, which allowed all affordable units in a project to be restricted at up to 130 percent AMI."
The most recent step came this fall. An HPD rule amendment effective September 19, 2026 lets projects that filed on time and were already approved as Option C or G switch to Option A, B, E or F.
So an extension project can't have all of its affordable units at 130 percent AMI. Option D covers homeownership projects. Each rental option the extension allows, A, B, E and F, requires some units at a lower AMI ceiling.
HPD's 421-a page describes each option as a minimum share of units at up to a given AMI level. The table below lines up the rental options with HPD's 2025 maximum two-bedroom rent and its 2026 three-person income limit at each option's lowest AMI ceiling. Both figures are caps, and a unit's actual rent can come in lower.
| Option | Minimum affordable share and AMI ceilings | Max 2BR rent at lowest ceiling, 2025 chart | 3-person income limit at that ceiling, 2026 |
|---|---|---|---|
| A | 25%: at least 10% up to 40% AMI, 10% up to 60%, 5% up to 130% | $1,458 | $61,080 |
| E | 25%: at least 10% up to 40% AMI, 10% up to 60%, 5% up to 120% | $1,458 | $61,080 |
| B | 30%: at least 10% up to 70% AMI, 20% up to 130% | $2,551 | $106,890 |
| F | 30%: at least 10% up to 70% AMI, 20% up to 130% | $2,551 | $106,890 |
| C | At least 30% at up to 130% AMI | $4,738 | $198,510 |
| G | At least 30% at up to 130% AMI | $4,738 | $198,510 |
Brownstoner's description, 20 to 30 percent at around 130 percent AMI, fits Option C or G most closely. Those are the two options the 2031 extension excludes. Under Options B and F, the same building could still have a large group of units at up to 130 percent AMI, but at least one in ten apartments would be capped at 70 percent AMI. Under A or E, at least one in ten would be capped at 40 percent and another one in ten at 60 percent.
HPD notes that its chart shows the maximum rent at each AMI level and that actual rents vary by program. The affordable units are typically marketed through NYC Housing Connect, and the AMI columns in that listing will show which structure the building is using.
The income limits also cut the other way. A household that earns too much for a 40 or 60 percent unit can still fall within a 130 percent band, and a 130 percent unit might cost close to what a comparable market-rate apartment rents for. Before you apply, it helps to know which band your household income falls in on HPD's AMI chart.
Our earlier rent freeze breakdown noted that most Park Slope apartments are not rent stabilized. A new 421-a building is one place where stabilization does apply, and it applies differently depending on the unit.
According to HCR's Fact Sheet #41, affordable units in a 421-a(16) building stay affordable and rent stabilized for 35 years, or 40 years for qualifying large projects in enhanced affordability areas. HPD states that a market-rate unit is subject to rent stabilization unless, without the 421-a benefits, the owner could remove it from stabilization upon vacancy because its rent exceeds the legal limit. HCR's initial registration instructions add that a first market rent at or above the decontrol threshold is permanently exempt, while a first rent below it is stabilized.
That matters this year because of Rent Guidelines Board Order #58. Dated June 25, 2026, it sets a 0 percent increase for both one-year and two-year leases beginning between October 1, 2026 and September 30, 2027. The order says its adjustments also apply to units in buildings receiving a 421-a partial tax exemption.
The guideline governs rent adjustments on stabilized units. It doesn't set the starting rent. At a new building, the first rent on an affordable unit comes from its program tier, and the first rent on a market unit is what determines whether that unit is stabilized at all. Two apartments on the same floor can sit under different rules.
There's one more practical issue for anyone who is planning a move date. Hoodline reported on October 14 that the building was being marketed for rentals before it had a certificate of occupancy. The outlet also cited the NYC Department of Buildings rule that a building may not legally be occupied until the city issues a Certificate of Occupancy or a Temporary Certificate of Occupancy.
The DOB's public records are the place to check. The Buildings Information System certificate page for 263 Prospect Avenue, BIN 3430633, showed no certificates of occupancy on file in late October. Newer certificates are issued through DOB NOW, and a query of the city's DOB NOW certificate of occupancy dataset, last updated October 31, 2026, returned no records for that BIN.
If you're touring, keep a short list of questions:
You can reach the leasing office at 929.379.3750.
The building has a rooftop with barbecue stations and lounge space, a fitness center, a golf simulator, a resident lounge and event space, a children's playroom, a business suite, a pet spa, bike storage and parking. Brownstoner reported that permits show 180 parking spaces. New York YIMBY places it within walking distance of the F, G and R at 4th Avenue–9th Street and the R at Union Street.
The site has a history of its own. As Brownstoner recounted, Grand Prospect Hall, a Renaissance Revival banquet hall built in 1902 and famous for its "where all your dreams come true" commercials, was sold to Gowanus Cubes LLC for $22.5 million and demolished in 2022 after a landmarking campaign fell short.
Is every apartment at The Grand Prospect rent stabilized? Affordable units in a 421-a(16) building are stabilized. A market-rate unit is stabilized only if its first rent comes in below the decontrol threshold, according to HCR.
Does the 0 percent freeze lower my first rent? Order #58 sets 0 percent adjustments for stabilized leases that begin from October 1, 2026 through September 30, 2027. The starting rent is set separately, by program tier for affordable units and by the initial registered rent for market units.
Where do I check my income against the tiers? On HPD's Area Median Income page, which lists 2026 income limits by household size.
This post is general information, not legal, tax or financial advice. Program rules and eligibility depend on your situation, so confirm the details with the right professional or the agency that runs the program.
If you're weighing The Grand Prospect against other Park Slope rentals and want someone to compare leases, stabilization status and move-in timing with you, in English or Spanish, Nelson Aybar can help. Get help in a New York minute — Contact Nelson.
Stay up to date on the latest real estate trends.
Hardworking, goal-driven, and passionate Real Estate Professional has more than 18 years of experience in Business Operations and Real Estate Sales. Possess a unique ability to duplicate success within diverse marketplaces. Committed to providing the highest level of service possible. Contact him to learn more!