Impact fees are one-time charges that a city, county, or special district imposes on new development to pay for the public infrastructure that development will require. A typical new single-family home carries roughly $6,000 to $9,000 in impact fees nationally, but the figure swings wildly by location and tops $100,000 in some high-cost markets. The underlying idea is simple: growth should pay for the roads, pipes, parks, and schools it demands, instead of pushing those costs onto existing residents through higher taxes.
What the Money Can Pay For
Impact fees fund capital improvements that expand a community’s physical capacity to serve new residents or businesses. Transportation is a big share, covering new roads, intersection upgrades, and traffic signals. Water and sewer systems receive heavy funding too, paying for treatment plant expansions, pump stations, and main-line extensions into previously undeveloped areas. The fees also flow toward fire stations, police substations, libraries, parks, playgrounds, and athletic fields. School construction is another common use, especially in fast-growing suburbs where new homes fill classrooms faster than existing budgets can handle.
One restriction runs through nearly every jurisdiction: the money can only buy new capacity. Operating expenses like staff salaries, fuel, routine maintenance, and administrative overhead are off-limits. Patching a pothole or replacing an aging pipe doesn’t qualify. The fee must fund something that adds capacity to serve the new development, not maintain what already exists.
Impact Fees vs. Connection Fees
Developers often see both impact fees and connection fees (sometimes called tap fees) on the same project, and treating them as the same thing is an expensive mistake. An impact fee funds system-wide capacity expansion, like a larger water treatment plant to handle demand from a new subdivision. A connection fee covers the physical cost of hooking a specific property into an existing utility line, including labor, materials, and the meter.
The legal rules are different too. Impact fees must satisfy constitutional proportionality standards and typically require a formal study justifying the amount. Connection fees are generally treated as service charges and face less scrutiny. Challenge the wrong fee under the wrong framework and you lose time and money.
How the Amount Gets Calculated
Most jurisdictions build their fee schedules around a unit of measurement called an equivalent residential unit, or ERU. One ERU represents the average demand a single-family home places on a given system, whether that’s water use, sewer flow, road trips, or park acreage. A single-family home equals one ERU by definition, and every other land use is converted into ERU equivalents based on its relative demand.
A 10,000-square-foot retail store that generates three times the traffic of a typical home would be assessed at three ERUs for transportation impact fees. A small apartment might count as 0.6 ERUs for water and sewer because of lower average consumption. The local government multiplies the number of ERUs by a per-unit fee derived from the cost of planned infrastructure improvements divided by the total new capacity those improvements will create.
Jurisdictions typically set fees at or below the full cost of the infrastructure attributable to new development. The calculation requires projecting future growth, estimating the cost of facilities needed to serve that growth, and dividing those costs proportionally across anticipated new development. This is where things get contentious. Aggressive growth projections can inflate fees; conservative ones leave infrastructure underfunded.
The Nexus Study
Before a local government can impose or update impact fees, most states require it to complete a formal nexus study and adopt a capital improvement plan. The nexus study is the analytical backbone of the fee program. It must demonstrate three things: that new development creates a need for additional facilities, that the planned improvements will benefit the development being charged, and that the fee amount is proportional to each land use’s share of the cost.
The capital improvement plan identifies the specific projects the fees will fund, with approximate locations, sizes, timelines, and cost estimates, usually programmed over at least five years. Fees adopted without a defensible nexus study are vulnerable to legal challenge, and courts have invalidated fee programs where the underlying analysis was outdated, speculative, or failed to account for other funding sources.
Who Can Charge Them
Authority to charge impact fees flows from state-level enabling legislation down to local governments. City councils and county boards are the usual bodies that adopt fee ordinances. Specialized districts also commonly hold this power. School districts impose fees for new classroom construction, and water and sewer authorities collect fees to extend utility networks into newly developed areas.
Not every state grants the authority. Alaska, Connecticut, Kansas, Kentucky, and North Dakota lack specific statewide enabling legislation for general impact fees. In those states, local governments sometimes rely on broader home-rule or zoning powers to negotiate development contributions, but the legal footing is shakier. Pennsylvania authorizes transportation impact fees but not general-purpose ones.
Where multiple entities charge fees on the same project, each must demonstrate its own authority and link its fee to the specific service it provides. A developer building homes in an area served by both a city and a separate school district might pay separate transportation, parks, and school impact fees, each backed by its own nexus study.
Constitutional Limits
Three U.S. Supreme Court decisions set the constitutional guardrails for impact fees, and they’re the starting point for evaluating whether any particular fee is legally defensible.
Essential Nexus
In Nollan v. California Coastal Commission (1987), the Court held that a permit condition must have an “essential nexus” to the government’s legitimate regulatory interest. Without a logical connection between the condition and the development’s actual impact, the Court called the condition “an out-and-out plan of extortion.”1Justia. Nollan v. California Coastal Commission Applied to impact fees, this means a government cannot charge a developer for infrastructure unrelated to the demand the project creates.
Rough Proportionality
In Dolan v. City of Tigard (1994), the Court added a second requirement: rough proportionality. The government must make “some sort of individualized determination that the required dedication is related both in nature and extent to the proposed development’s impact.”2Justia. Dolan v. City of Tigard No precise math is required, but the burden must be reasonably scaled to what the development actually causes. A local government cannot load the full cost of a major road widening onto one developer when dozens of other projects contribute to the traffic.
Monetary Exactions
In Koontz v. St. Johns River Water Management District (2013), the Court closed a loophole by ruling that the essential-nexus and rough-proportionality tests apply to demands for money, not just physical land dedications. Monetary exactions get the same constitutional scrutiny, even when the government ultimately denies the permit rather than granting it with conditions.3Legal Information Institute. Koontz v. St. Johns River Water Management District
Together, these cases mean every impact fee must clear two hurdles: it must be logically connected to the development’s actual impact, and the amount must be roughly proportional to that impact. Fees that fail either test risk being struck down as unconstitutional takings.
When Payment Is Due
Timing varies by jurisdiction and is defined in the local ordinance. The most common trigger is the issuance of a building permit, when the local government calculates the fee based on square footage, unit count, or land-use classification. Collecting at the permit stage secures funding before the development starts generating demand.
Some jurisdictions push collection later. For large subdivisions, the fee might not come due until a final plat is approved or land-use documents are recorded, when the exact scope of the project is clearer. Others wait until the certificate of occupancy, the document that authorizes a building to be inhabited or used. A few jurisdictions split payments across multiple milestones to ease the front-end burden on developers during early construction phases.
How Much to Expect
Impact fees for a single-family home range from nothing in jurisdictions that don’t impose them to well over $100,000 in high-cost markets. The national average sits around $6,000 to $9,000 per home, but that figure masks dramatic regional variation. California jurisdictions tend to charge the highest fees in the country, while many communities in states without enabling legislation charge nothing at all.
Commercial and industrial projects face fees scaled to their projected impact and can run substantially higher. A large retail center generating significant traffic and utility demand might owe fees in the tens or hundreds of thousands of dollars across multiple categories. The total depends on how many types of fees the jurisdiction imposes and how aggressively its nexus study prices the infrastructure costs attributable to new development.
Credits When a Developer Builds the Infrastructure
When a developer builds infrastructure the jurisdiction would otherwise need to fund, the developer can typically claim a credit against the impact fees owed. This most often happens with oversized improvements. If a developer installs a water main large enough to serve not just their subdivision but also future development beyond it, the excess capacity benefits the broader community, and the developer shouldn’t bear that cost alone.
Credits also apply when a developer dedicates land for public use, like a park site or road right-of-way included in the capital improvement plan. The value of the dedication offsets the fee dollar for dollar in most ordinances. Some jurisdictions formalize these arrangements through reimbursement agreements, where a developer who fronts the cost of a shared improvement receives payments from impact fees collected on future projects that benefit.
Getting credits right requires careful documentation and, ideally, a written agreement with the jurisdiction before construction begins. Developers who build improvements without a prior agreement sometimes find it difficult to claim credit after the fact.
Refunds for Unspent Fees
Most states that authorize impact fees also require that the money be spent within a set number of years or refunded. Deadlines usually fall between six and ten years from the date of collection, depending on the state statute. The fees must be held in segregated accounts rather than commingled with general revenue, and jurisdictions are generally required to track which fees came from which development.
If the jurisdiction fails to spend the fees on qualifying capital improvements within the deadline, the original payer (or their successor in interest) can claim a refund. Some states allow an extension if the jurisdiction documents a reasonable cause for the delay and identifies a specific future spending date, but even those extensions have outer limits. Worth tracking if you’ve paid impact fees, because local governments don’t always proactively issue refunds when deadlines pass.
Affordable Housing Waivers
A growing number of jurisdictions reduce or waive impact fees for developments that include affordable housing. The details vary, but the most common approach ties eligibility to household income thresholds, typically 80 percent of the area median income as defined by the U.S. Department of Housing and Urban Development.4U.S. Department of Housing and Urban Development. Impact Fees and Housing Affordability – A Guidebook for Practitioners
Reductions range from partial discounts of 50 to 60 percent to complete waivers, depending on the jurisdiction and the project’s affordability level. Some communities limit waivers to the affordable units within a mixed-income project rather than applying the reduction to the entire development. Others cap the total number of waivers they’ll grant annually to manage revenue impacts.
Whether the waived revenue must be replaced from another source depends on the state. Some require the jurisdiction to backfill the lost fee revenue from general funds. Others allow waivers without replacement, which means existing ratepayers effectively subsidize the affordable units’ share of infrastructure costs.
Effect on Home Prices
Impact fees don’t stay on the developer’s balance sheet. Like other construction cost inputs, they pass through to the end buyer or renter. A $15,000 impact fee on a new home doesn’t just add $15,000 to the price; it adds that amount plus the developer’s carrying costs and margin. In markets where new construction already struggles with affordability, impact fees raise the floor price at which a builder can deliver a home profitably.
This creates a tension every community imposing impact fees must navigate. The fees exist to make sure new residents pay for the infrastructure they need, but if the fees price out the residents who would live there, the community ends up with infrastructure plans and no rooftops to serve. Higher-cost jurisdictions have seen this dynamic play out most sharply, where combined regulatory and fee costs can account for a significant percentage of a new home’s final sale price.
Challenging an Impact Fee
Developers who believe a fee is excessive or improperly calculated have legal options rooted in the Nollan, Dolan, and Koontz framework. The most direct path is challenging the fee’s nexus or proportionality. If the fee funds infrastructure unrelated to the development’s actual impact, or if the amount exceeds what the project’s demand justifies, the developer can argue the fee violates the Fifth Amendment’s protections against uncompensated takings.5Federal Highway Administration. Essential Nexus, Rough Proportionality, and But-For Tests
The practical complication is that many fee ordinances require payment before the permit issues. The developer often must pay under protest and then seek a refund or credit through administrative appeal or litigation. Waiting to challenge the fee without paying can stall the entire project, and carrying costs on undeveloped land pile up fast. Some jurisdictions offer an independent fee review or administrative hearing process, but availability and formality vary widely.
Where the underlying nexus study is weak, outdated, or based on speculative growth projections, developers have the strongest ground. Courts have been willing to invalidate fee programs where the government could not produce individualized findings connecting the fee amount to the specific development’s impact. The Koontz decision added leverage by making clear that monetary demands are subject to the same scrutiny as physical land dedications, regardless of whether the permit is ultimately granted or denied.3Legal Information Institute. Koontz v. St. Johns River Water Management District