Tennessee's wealthiest county and one of the fastest-growing in the Southeast — home to a uniquely layered three-part development fee structure that can exceed $16,000 per new home permit.
Williamson County is consistently ranked among the nation's highest-income and fastest-growing counties. Anchored by the city of Franklin to the south of Nashville, the county has seen its household count grow by more than 55% between 2010 and 2025 — a pace far outstripping the statewide average of 17%. A November 2025 housing study projected a shortfall of more than 10,000 units by 2030, underscoring just how acute development pressure remains.
The county's housing stock of 133,421 units leans heavily toward detached single-family homes, which account for roughly 72% of the total. Median home values as reported by the U.S. Census Bureau stood at $777,800 as of 2023, but active resale listings tracked by Redfin reached a median of approximately $975,000 in late 2025. Typical new construction in the county runs 2,800–3,000 square feet or larger.
For developers and builders, Williamson County's fee environment is the most complex and most costly in Middle Tennessee. Every new residential building permit triggers two county-wide Adequate Facilities Taxes totaling $2.00 per square foot, plus a separately calculated Education Impact Fee that varies by home size and school district location. Together, these three charges can easily exceed $16,000 on a single large-lot permit — and that is before any additional city-level fees within Franklin, Brentwood, or Nolensville.
The Education Impact Fee — adopted by the County Commission in November 2016 and upheld through litigation by the Tennessee Court of Appeals in 2020 — is recalculated every three years by independent consultants. In February 2025, commissioners authorized a new study to evaluate whether increasing the Adequate Facilities Tax would require offsetting credits against the Education Impact Fee rate, signaling potential changes ahead.
Local reporting and public records covering Williamson County's development fee landscape.
A study by Bowen National Research presented at the Williamson Inc. Keys to Housing event found that Williamson County's household count grew 55% between 2010 and 2025 — triple the statewide rate. The county is projected to need more than 10,000 additional units by 2030, with a median Franklin listing price of $875,000 and a countywide median exceeding $1.3 million making affordability the central challenge.
Read Full ArticleThe Williamson County Board of Commissioners unanimously approved a resolution directing the County Mayor to solicit proposals for a study examining whether increasing the commercial rate of the Adequate Facilities Tax would require crediting back revenue collected under the Education Impact Fee — a legal balancing requirement that could reshape the county's entire development fee structure going forward.
Read Full ResolutionAfter a more than two-year legal battle, the Tennessee Court of Appeals affirmed that Williamson County has the authority to collect its Education Impact Fee from residential developers. The ruling, which followed an initial 2019 Chancery Court victory for the county, settled a challenge from the Home Builders Association of Middle Tennessee and cleared the county to collect more than $8.8 million in fees that had accumulated during the litigation.
Read Full ArticleBuilding a new single-family home in Williamson County triggers fees at three distinct levels. First, there is the county-wide Adequate Facilities Tax (AFT) at $1.00 per square foot, funding general public facilities. Second is the Adequate School Facilities Privilege Tax — also $1.00 per square foot, dedicated to schools — for a combined county privilege tax total of $2.00 per square foot. On top of these, a separately calculated Education Impact Fee applies on a graduated scale based on the square footage of the home and whether the project falls within the Franklin Special School District. Williamson County imposes the highest combined development taxes and fees on new home construction of any county in Tennessee.
* Adequate Facilities Tax total of $2.00/sq ft reflects two $1.00/sq ft privilege taxes (general facilities and school facilities) collected at the county level. Education Impact Fee estimate is based on the graduated fee schedule for homes between 2,500 and 3,000 sq ft, as adopted by the Williamson County Board of Commissioners and periodically updated by TischlerBise impact fee studies. City-level impact fees for Franklin, Brentwood, and Nolensville are separate and not reflected above. Building permit fees, plat review fees, and utility connection charges are also not included. Sources: Williamson County School Impact Fee Project · Williamson County Building a Home. Always verify current rates with the Williamson County Building Codes Department prior to finalizing project pro formas.
Incorporated municipalities within Williamson County — each with its own development review authority and, in some cases, additional fee ordinances.
The county seat of Williamson County, Franklin does not independently levy a city-level impact fee on new residential construction. Developers building within Franklin city limits are subject to the county-wide Adequate Facilities Tax of $2.00 per square foot — covering general public facilities and schools — plus the county's graduated Education Impact Fee, which funds school capacity expansion. Combined, these county fees typically total ~$18,000 on a standard new single-family home.
Brentwood does not impose a separate city-level development impact fee on new residential construction. New builds in Brentwood are subject to the county-wide Adequate Facilities Tax of $2.00 per square foot — split equally between general public facilities and school facilities — plus the county's graduated Education Impact Fee, which scales with home size and funds school capacity. Combined county fees on a typical new home in Brentwood average approximately $18,000.
Nolensville does not levy a separate city-level impact fee on new residential construction. Builders in Nolensville pay the county-wide Adequate Facilities Tax of $2.00 per square foot — covering both general public facilities and school facilities — along with the county's graduated Education Impact Fee tied to home size. These county charges fund roads, parks, public safety, and school capacity. Total county fees on a typical new Nolensville home average approximately $16,100.
Williamson County carries the highest combined development fees in Middle Tennessee — a three-part structure of two privilege taxes plus a graduated Education Impact Fee that resets every three years. Add city-specific review requirements in Franklin, Brentwood, and Nolensville, the Franklin Special School District boundary's effect on fee calculations, and an active legislative study that could restructure rates, and the stakes for accurate pro forma modeling have never been higher.