Home prices in Idaho are surging. Over the past year, median home values in large cities like Boise and Nampa have increased by as much as 38 percent. Those higher prices, combined with the end of a property tax break granted during the pandemic, mean that many Idahoans are now seeing dramatically higher property tax bills. In response, the state legislature passed a controversial bill aimed at tax relief this spring.

The new law is unusual compared with typical approaches to property tax relief, and some local leaders are warning that its revenue limitations could ultimately force them to raise taxes or fees elsewhere, or cut essential services. As cities and counties assess how the law will affect their budgets, one city has even put a temporary halt on development.

Among other things, HB 389 places caps on local revenue growth. Idaho already had a 3 percent cap on local property tax revenue growth, but the cap didn’t apply to new development. That’s no longer the case—now, allowable property tax revenue growth from new construction will be calculated on only 90 percent of its assessed value. In addition, existing properties returning to the tax rolls under programs to encourage new economic development will contribute only 80 percent of their assessed value to the taxing district’s allowable revenue base. The law also imposes an 8-percent cap on localities’ total annual revenue growth, regardless of the amount of new development.

The bill’s author, House Majority Leader Rep. Mike Moyle, has said the new changes would stop the rapid development growth in Idaho from driving up existing homeowners’ tax bills. Even with the old revenue cap in place, homeowners saw their bills rise faster because home values are rising rapidly while the value of nonresidential property is not. “Right now in Idaho, when somebody builds a new house next to you, your taxes go up,” he told a local news station in May.

Although Moyle argued the bill “fixes that problem,” that’s not the result homeowners are likely to see. Properties are reassessed every year in Idaho, and an existing homeowner’s bill based on that value is more affected by the overall market rather than whether a new house is built nearby. Areas with a lot of growth might experience faster appreciation in home values, and thus faster growth in property tax bills, but restricting taxation of new property will not provide a direct benefit to existing homeowners.

What’s more, the cap on taxes collected from new development actually burdens existing homeowners more by artificially deflating the tax bills for new homes while taxing existing homes at full value.

Officials in fast-growing places are especially worried. Cities must provide newly developed areas with services such as water and sewer, public safety, and street maintenance. Up until this year, revenue collected from those new properties helped pay for that, but now cities are limited in their ability to pay for growth.

The restriction on tax revenue from new development is an unusual approach, said Lincoln Institute Senior Fellow Joan Youngman. While many states limit the total tax revenue a city or town may collect each year, Youngman says that increases are often permitted to reflect the addition of new construction to the tax base.

“Allowing a city’s total tax revenue to keep pace with new development enables the jurisdiction to raise funds to meet the service needs of a larger population without increasing taxes on the existing residents whom the limits are designed to protect,” Youngman said.

Responses to the Bill

Local leaders in Idaho were caught off guard by the bill, which was introduced during the last week of the legislative session in May. The bill faced bipartisan opposition but ultimately passed by a ratio of two to one. Legislators who voted against it said they were concerned it would erode local governments’ ability to provide services, particularly in rapidly growing communities.

That issue is perhaps most pressing in Treasure Valley, the most populous region of Idaho, which encompasses the fast-growing Boise metro area. The city of Nampa has grown by 36 percent over the last decade. That influx of new residents, combined with historically low interest rates, has fueled a home building boom. Under normal circumstances, when such growth occurs, tax rolls increase accordingly. But capping revenue from new construction now means that localities will have to look elsewhere for the funds needed to cover costs related to growth—or they’ll have to cut public safety and other critical services.

Cities and counties across the state are still evaluating how the new caps will impact their revenues. Nampa Finance Director Douglas Racine estimates that HB 389 will reduce revenues from new construction by $1 million. So far, city leaders have responded by increasing impact fees, which are tied to new construction, and are considering other ways to balance the budget without raising costs for existing homeowners.

Northwest of Nampa, the city of Caldwell (pop. 59,000) has enacted the most aggressive response to the legislation so far with a 120-day moratorium on annexations and new development approvals. Supporters said the pause would help give the city, which grew 26 percent between 2010 and 2019, time to come up with a new plan for how to handle growth in the face of the “imminent peril” posed by the state legislation. The move was opposed by builders who warned that pausing development could cause home prices to soar even higher.

Relief by Any Other Name

The new state law also includes two changes aimed at property tax relief. It increases the current cap on the homeowner’s exemption, the portion of a home’s value that is spared from taxation, from $100,000 to as much as $125,000 (depending on the assessed value). And it increases the maximum benefit provided by the circuit breaker program, which offers tax relief to seniors and homeowners whose property tax bills exceed a certain share of their income.

However, starting in 2022, anyone whose home is valued at more than 125 percent of the area median will not be eligible for the circuit breaker program. Opponents warned that adding the home value provision would unfairly deprive people from tax relief if they have fixed incomes but happen to live in hot housing markets. Further, restricting cities’ ability to generate revenue from new construction will erode the tax base over time.

“In the final analysis, the financial benefit to taxpayers will be difficult to quantify and will very likely be negligible,” Nampa’s Racine wrote in a June budget report.

Mayor Debbie Kling of Nampa hopes to rally other Treasure Valley leaders to support property tax relief next year to address the issue from another angle: changing the way homes are assessed. Currently, Idaho law requires that homes be assessed at market value. Kling supports an amendment to the state constitution that would limit how much a home’s assessed value can increase each year. She lobbied for the change this year but hopes next year it will have more support.

“It’s frustrating,” said Kling. “We have the ability to do something that provides actual tax relief to our citizens. Unfortunately, this year, a few in the legislature just wanted to point their fingers at the cities and say our budgets were too high.”

However, unlike revenue limits, which affect only the amount of tax collected, assessment limits can distort the taxes due on similar properties. For example, in California, properties are generally only reassessed at market value upon sale, which means that longtime property owners pay artificially low rates compared to newer purchasers. The 50-State Property Tax Comparison Study by the Lincoln Institute and the Minnesota Center for Fiscal Excellence examines 29 large cities in which state-imposed assessment limits favor longtime owners by limiting the growth in the assessed value of individual properties.

Youngman points out that when housing values rise precipitously it is important to adjust tax rates to moderate the effect on tax bills. In Massachusetts, Proposition 2½ imposes both a revenue limit and a rate limit but maintains fair market value as the basis for assessments. This system has remained stable for over three decades. “This shows that limitations can be based on accurate assessments,” Youngman said.

Liz Farmer is a fiscal policy expert and journalist whose areas of expertise include budgets, fiscal distress, and tax policy. She is currently a research fellow at the Rockefeller Institute’s Future of Labor Research Center.

Photograph: Municipal leaders in Idaho say new legislation intended to provide property tax relief will force them to cut essential services or raise taxes and fees elsewhere. Credit: picmax via iStock/Getty Images Plus.