California Impact Fees: Nexus, Deadlines, and Challenges

California impact fees are monetary charges that cities, counties, school districts, and special districts impose on new construction to pay for the public infrastructure that growth creates demand for. They are authorized and constrained by the Mitigation Fee Act, which begins at Government Code Section 66000, and after the U.S. Supreme Court’s 2024 decision in Sheetz v. County of El Dorado, they are also subject to constitutional nexus and proportionality review even when adopted by ordinance.¹ The rules below cover what the fees can fund, how they must be justified, when they are collected, what agencies have to do with the money, and how a developer or property owner can challenge one.

What Impact Fees Fund and Why They Are Not Taxes

Section 66000 defines a development impact fee as a monetary charge, other than a tax or special assessment, that a local agency imposes on a developer in connection with project approval to cover the cost of related public facilities.² In practice, fee revenue pays for roads and transportation improvements, parks, water and stormwater systems, sewer infrastructure, fire and police stations, and libraries.

The fee-versus-tax line matters because California’s Constitution requires a two-thirds vote of the electorate to impose a special tax. Impact fees avoid that vote only because they are structured as regulatory charges tied to a specific development’s burden on public services. A fee that cannot show that connection is vulnerable to being struck down as an unauthorized tax.

Cities, counties, school districts, special districts, and other political subdivisions can all impose impact fees.² Each one draws authority from the police power, with the Mitigation Fee Act supplying the procedural and substantive limits.

The Nexus and Proportionality Requirement

When a local agency establishes, increases, or imposes a fee, Government Code Section 66001 requires it to do four things: state the purpose of the fee, identify the specific facilities the fee will fund, show a reasonable relationship between the fee’s use and the type of development charged, and show a reasonable relationship between the need for the facility and that type of development. The fee amount must be reasonably related to the cost of the facility attributable to the specific development,³ and no fee can exceed the estimated reasonable cost of providing the facility it funds.⁴

Agencies document those relationships in a “nexus study.” Section 66016.5 requires a nexus study to be adopted before the associated fee takes effect, and the study must be updated at least every eight years.⁵ A stale study that no longer reflects current construction costs or growth projections is a common weakness in legal challenges.

How Sheetz Changed the Analysis

For years, California courts treated fee schedules adopted by a city council through the normal legislative process differently from one-off conditions imposed by a planning commission. The U.S. Supreme Court rejected that split in Sheetz v. County of El Dorado (2024), holding that the Takings Clause “does not distinguish between legislative and administrative land-use permit conditions.”¹ A fee schedule adopted by ordinance now faces the same constitutional nexus and proportionality scrutiny that applies to project-specific exactions.

The Court left to the state courts the question of how precisely a legislatively imposed fee must be tailored.¹ Early California trial-court litigation after Sheetz has already resulted in at least one fee program being invalidated, so the quality of the nexus study behind any fee has become more important, not less.

When Developers Actually Pay

Fee timing is one of the most frequently misunderstood pieces of the Act. For residential development, Section 66007 bars a local agency from collecting fees before the date of the final inspection or the date the certificate of occupancy is issued, whichever is first.⁶ The fee is usually imposed as a condition of approval much earlier, but the money does not change hands until near completion.

Two exceptions matter. An agency can collect earlier if it has established an account with appropriated funds and adopted a construction schedule for the improvements, or if the fees reimburse the agency for expenditures it already made.⁶ Utility connection fees can also be collected when the developer applies for service.

Deferred Collection for Designated Residential Projects

SB 937 (2024) added Section 66007(c) to shift timing further in favor of certain housing. For “designated residential development projects,” which the statute defines to include 100-percent affordable housing, density bonus projects, low-barrier navigation centers, and projects of 10 or fewer units, a local agency cannot collect fees until the first certificate of occupancy or first temporary certificate of occupancy is issued, whichever comes first.⁶ The amount owed is the same fee the developer would have paid at building permit, with no interest or additional charges on the deferred balance. That shift directly reduces carrying costs on smaller and affordable projects.

How Agencies Must Handle the Money

Collected fees are not general revenue. Section 66006 requires every dollar to be deposited into a separate capital facilities account, kept apart from the agency’s general fund. Interest earned on the funds stays in the account and can only be spent on the purpose for which the fee was collected.⁷

Annual Reporting

Within 180 days after the end of each fiscal year, the agency must publish a report for every fee account showing the fee amount, beginning and ending balances, fees collected and interest earned, each public improvement the fees were spent on, any interfund transfers or loans, and refund amounts.⁷ The governing body then reviews the information at the next regularly scheduled public meeting held at least 15 days after the report becomes available.

The Five-Year Findings and Refund Rule

For the fifth fiscal year after the first deposit into an account, and every five years after that, the agency must make formal findings about any unexpended money. Those findings have to identify the fee’s purpose, demonstrate that a reasonable relationship still exists between the fee and that purpose, list the anticipated funding sources needed to complete unfinished improvements, and estimate when that funding will arrive.³

Miss the deadline and the agency must refund the unexpended money to the current property owners on a pro rata basis.³ The five-year clock runs on its own, and the refund obligation is not something that can be cured after the fact.

How to Challenge a Fee

Section 66020 lays out a strict path for anyone who thinks a fee is unlawful or excessive. The steps have to happen in order and inside short windows.

First, pay the fee in full or provide satisfactory evidence that payment arrangements are in place. Second, at the same time, serve written notice on the governing body stating that payment is being made under protest. The notice must describe the factual basis for the dispute and the legal theory behind the challenge. The protest must be filed at the time of project approval or within 90 days after the fee is imposed.⁸

Filing a protest cannot be used against the project. Section 66020 expressly prohibits a local agency from relying on the protest as a basis to deny a map, permit, zone change, or other approval tied to the project.⁸

A protest alone is not the challenge. The developer still has to file a court action within the statute of limitations set by Section 66020. Waiting until the project is finished to decide whether to litigate is not an option, which is why counsel generally gets involved when the fee is first imposed rather than after the protest window closes.

Charges the Mitigation Fee Act Does Not Cover

Not every charge a developer pays is governed by the Act. Four categories are handled under separate rules, and a protest strategy built on Mitigation Fee Act requirements will fail if the charge actually sits in one of them.

Park dedication fees collected under Section 66477 (the Quimby Act) in connection with subdivision approvals follow their own requirements.²
Processing and permit fees charged for the agency’s cost of reviewing applications are outside the Act, though they are subject to a separate cost-reasonableness standard.
Fees collected under negotiated development agreements have their own statutory authority and are not subject to Mitigation Fee Act procedures.²
Water and sewer connection fees are governed by Section 66013. They still have to meet a cost-reasonableness standard and follow certain public hearing requirements, but the nexus study, five-year findings, and segregated account rules of the Mitigation Fee Act do not apply to them.⁹

Identifying the correct framework before paying or protesting is the first move for a developer, and the first compliance question for the agency.

1
Justia. Sheetz v. El Dorado County
2
California Legislative Information. California Code GOV 66000 – Fees for Development Projects
3
California Legislative Information. California Code GOV 66001 – Establishing, Increasing, or Imposing Fees
4
California Legislative Information. California Code GOV 66005 – Limitations on Fees
5
California Legislative Information. California Code GOV 66016.5 – Impact Fee Nexus Study Requirements
6
California Legislative Information. California Code GOV 66007 – Fees on Residential Development
7
California Legislative Information. California Code GOV 66006 – Deposit and Reporting Requirements
8
California Legislative Information. California Government Code 66020
9
California Legislative Information. California Code GOV 66013 – Water and Sewer Fees