TaxProper

Acquired

TaxProper helps large Real Estate owners manage their property taxes.

Summer 2019Founded 20198 peopleChicago, IL, USA

taxproper.com/ ↗See on the Idea Map Real Estate and Construction momentum

About

TaxProper is an enterprise SaaS solution that acquires real-time property tax data, encodes local tax rules, and contains all of the operational workflows associated with property tax management. Our core products automate property tax payments, forecast future property tax liability, and help large real estate operators manage their property tax appeals.

From their website

as of Jun 7, 2026taxproper.com ↗

SaaSSubscription

TaxProper is positioned as a system of intelligence for residential real estate, aimed at helping large real estate owners manage property taxes and make smarter investment decisions. The platform markets interoperability across ownership stages and emphasizes better data-driven outcomes for investors and property managers.

Mainstay Mainstay presents a unified platform that aggregates property data (comps, AVMs, market velocity, rents, operating costs) and provides underwriting and tax-related insights. It shows estimated values, rents, NOI, cap rate, IRR, and lists price review results, with an emphasis on interactive demos and one-system workflows for buying, owning, and selling across multiple property listings. The system connects various workflows (underwriting, property tax, listings, offers) and surfaces decision-ready metrics within a single interface.

Who it’s for: Large real estate owners, real estate investors, and property managers seeking integrated data, underwriting insights, and streamlined workflows for residential real estate portfolios.

Features

Integrated comps and AVM-based valuations
Underwriting and rent/expense modeling
Net yield, NOI, cap rate, and IRR calculations
Single platform for buy, own, sell workflows
Property tax and operating cost tracking
Interactive demo access
Exclusive inventory and listing management

Backed by notable investors and connected to large residential platforms; ongoing product emphasis on data-driven decisions and integrated broker workflows.

Founders · 2

Thomas DowlingCo-founder

Oxford

UIUC

Tom is the co-founder of FullSeam (W26). FullSeam automates work for corporate accounting teams. He previously co-founded TaxProper (S19), the leading property tax software for institutional real estate investors, which was acquired by Opendoor (NASDAQ: OPEN) for 8-figures in 2022. He advised the Mayor of Chicago and was appointed by Illinois Governor JB Pritzker to oversee a $700m/year state agency. He has a BA from UIUC and an MSc from Oxford, where he was a Rhodes Scholar.

LinkedIn ↗X ↗

Geoff SegalCo-Founder

Geoff is the co-founder of FullSeam (W26), the AI employee for finance and accounting teams. He previously co-founded TaxProper (S19), the leading property tax software for institutional real estate investors, which successfully exited to Opendoor (NASDAQ: OPEN) in 2022.

LinkedIn ↗