NYC Moves to 3D Records for Property Valuation

Few areas of municipal operations present as much complexity, political anxiety and opportunity as the property tax system, which stretches from planning and building permits to assessments and taxation. The complexity, driven in large part by the number of agencies and amount of critical information they process, causes frustrating delays and a sense of mystery around assessments that provokes concerns about fairness and a robust business around appeals.

The fundamental importance of the tax system, its tentacles in so many agencies and its effect on every resident, makes it particularly ripe for total technological reform. Over the last several years, digitization allowed several cities to take steps forward in terms of customer service.

The next set of reforms will be bolder thanks to new technologies that streamline processes through integration around place. Providing more robust transparency to residents and city workers alike, coupled with an expanded definition of place, will unlock greater fairness, transparency and value.

The New York City Department of Finance (DoF) has done just this, redefining place by moving from 2D to 3D records while using GIS to link together diverse systems into a single view. The very job held by Carmela Quintos, the city’s assistant commissioner of property valuation and tax mapping, shows how highly DoF values technological improvement.

In December 2023, DoF demonstrated the power of spatially linking information through an easy-to-use Property Information Portal (PIP) that provides one-stop shopping for owners, facilitating enhanced customer service and reducing department workloads. The portal helps interested parties verify building and land data for accuracy; view and challenge their assessments and exemptions; verify sales, mortgages and recordings; and trace the history of lot changes to their parcels. 

Quintos pointed out that in a city with air lots — those built on separate floors — set aside for future development and complex condominium structures, DoF’s 3D capabilities are critical. Tax parcels that sit above or below ground level, such as New York’s 290,000 condominium lots, cannot be displayed by a 2D map. In contrast, 3D maps show condominium tax lots by converting floor plans into 3D GIS, allowing assessors to see a building’s interior layout at different angles. They can verify the amenities available to different units that may affect value. In addition, 3D GIS assists the city in identifying air rights.

Public confidence in a governmental system requires that it be easily understood and that service requests are quickly fulfilled. Both are only possible when diverse systems are easily available in one digital location. Combining PIP and 3D GIS imaging accomplishes both.

New York’s portal supports analytics and other citywide authoritative applications that assist in accuracy and revenue recognition. Quintos emphasized the following substantial digital and analytic capabilities provided to staff:  

As a data collection tool. Field assessors can use the tax map to navigate and inspect property, verifying that the information on the map matches what they see. The field worker can see information on building size, age, use, stories, number of units and DoF construction type, as well as Department of Buildings information on permits for alteration, demolition and new construction, plus Planning Department information on land-use classifications.

As a modeling tool. Location enters all appraisal models. Spatial analysis helps locate the most suitable comparable properties and supports analysis of characteristics that affect value, such as distance to the nearest subway or parks. And 3D opens up the possibility of calculating property views or line-of-sight variables, which can affect value.

As a quality control tool. The tax map is used to validate that data is consistent with reality. In PIP, assessors can verify that the map information matches their assessment. Since PIP includes renderings of floor plans in 3D GIS, quality control extends to verifying that data at the more granular interior level.

Quintos and her team have shown a future where a department provides priority to spatial technology and invests in a way that builds internal capacity and external trust. And by connecting so much data together in one digital place, the city is prepared for when tools like generative AI provide easier access to and understanding of city data.

This story originally appeared in the November/December 2024 issue of Government Technology magazine. Click here to view the full digital edition online.