California’s SB 166, known as the No Net Loss Rule, requires every city and county to keep enough land in its housing element inventory to accommodate its remaining Regional Housing Needs Allocation at every income level, at every point during the planning period. If a local government approves a project at lower density than planned, downzones an inventoried parcel, or otherwise shrinks capacity, it must make written findings showing the rest of the inventory still covers the gap, or identify replacement sites within 180 days.1California Legislative Information. California Government Code GOV 65863 The compliance burden sits with the jurisdiction, not the applicant.
What Triggers the Rule
Two kinds of decisions set the statute in motion. The first is a formal density reduction: a rezoning, general plan amendment, or similar action that lowers the allowed density on a parcel listed in the housing element inventory. The second is a project-level shortfall: a developer builds fewer units, or units at a higher income level, than the housing element assumed for that site.2California Department of Housing and Community Development. SB 166: No Net Loss Law Either path puts the jurisdiction on the hook for findings and, if needed, replacement land.
The reach is broad. Administrative, legislative, and quasi-judicial actions all count if they cut planned residential capacity on an inventoried parcel. For developers, there is an important protection worth knowing: the statute explicitly bars a city from denying a housing project just because approving it would trigger the replacement site obligation.1California Legislative Information. California Government Code GOV 65863 The city has to figure out its own compliance; it cannot push the problem onto the applicant.
Why the Inventory and Income Tiers Matter
The findings required by SB 166 only make sense against the housing element inventory, so a quick orientation helps. Every California city and county must adopt a housing element listing each site available for residential development, with assessor parcel number, size, zoning, general plan designation, and the realistic number of units each site can accommodate.2California Department of Housing and Community Development. SB 166: No Net Loss Law Each site is assigned to an income category based on the density it can support, keyed to the jurisdiction’s RHNA.
California uses four income tiers tied to area median income: very low income (up to 50 percent of AMI), low income (50 to 80 percent), moderate income (80 to 120 percent), and above moderate income (over 120 percent).3California Department of Housing and Community Development. Income Limits The RHNA sets a specific number of units a jurisdiction must plan for in each tier. SB 166’s no net loss test runs separately for every tier, which is why swapping lower-income capacity for above-moderate capacity is a compliance problem even if the total unit count stays the same.
Written Findings Before Approving a Shortfall
Before approving a density reduction on an inventoried parcel, a city or county must adopt written findings backed by substantial evidence on two questions. The reduction has to be consistent with the adopted general plan, including the housing element. And the remaining inventory sites must still be adequate to accommodate the jurisdiction’s full RHNA share at every income level.1California Legislative Information. California Government Code GOV 65863
Vague assurances will not do. The findings have to quantify how many units of unmet need remain in each income tier and how many units the remaining inventory sites can actually accommodate in each tier. If a parcel planned for 50 lower-income units is approved for 30 above-moderate units, the findings must account for the 50-unit loss in the lower-income column and show whether other parcels close the gap.
The same income-level analysis applies when a project simply delivers fewer units, or units at a different income category, than the housing element assumed for the site. The jurisdiction still has to make written findings supported by substantial evidence that the remaining inventory accommodates RHNA by income level.1California Legislative Information. California Government Code GOV 65863 Skipping the findings is itself a violation and opens the approval to legal challenge.
The 180-Day Replacement Site Deadline
When the findings show the remaining inventory cannot absorb the loss, a hard clock starts. The jurisdiction has 180 days from project approval to identify and make available additional sites sufficient to cover the shortfall.1California Legislative Information. California Government Code GOV 65863 For a density reduction that leaves the inventory short, the rule is even tighter: the jurisdiction can proceed only if it simultaneously identifies replacement sites at equal or greater density so there is no net loss of residential capacity.
Replacement sites must match or exceed the lost capacity in both unit count and income level. If a parcel planned for lower-income housing is developed for above-moderate units, the replacement sites have to support at least as many lower-income units as were lost.2California Department of Housing and Community Development. SB 166: No Net Loss Law In practice this usually means rezoning parcels to higher densities or adding new sites that already carry the right zoning. Pointing to land that could theoretically be rezoned later does not satisfy the obligation.
Documentation of the replacement sites, with parcel numbers, zoning, and calculated densities, goes to the Department of Housing and Community Development for review. Missing the 180 days does not extinguish the duty. It puts the jurisdiction in violation of state housing law and in the path of enforcement and litigation.
Where SB 330 Fits In
SB 166 and SB 330 are often confused, so it is worth drawing the line. SB 330, the Housing Crisis Act of 2019, works through Section 66300 and prohibits affected cities and counties from changing a general plan designation, specific plan designation, or zoning to a less intensive use without concurrently adjusting other parcels to preserve residential capacity.4LegiScan. Bill Text CA SB330 2019-2020 Regular Session Chaptered “Less intensive use” is defined broadly to include cuts to height, density, or floor area ratio and increases to setback, lot size, or open space.
SB 166 focuses on parcels specifically listed in the housing element inventory and on individual project approvals that erode planned capacity. SB 330 reaches zoning and land use changes across the jurisdiction, inventoried or not. A city that tries to shrink housing capacity will usually trigger one, and sometimes both.
What Happens If a Jurisdiction Doesn’t Comply
HCD can revoke a jurisdiction’s housing element certification and refer the matter to the California Attorney General for legal action.5California Department of Housing and Community Development. Accountability and Enforcement Housing advocacy organizations and the state itself can also sue.
The harder consequence is the builder’s remedy. Under the Housing Accountability Act (Government Code Section 65589.5), a jurisdiction whose housing element is not in substantial compliance with state law loses the ability to deny a qualifying lower-income or moderate-income project on the ground that it is inconsistent with zoning or the general plan.6Association of Bay Area Governments. The Builder’s Remedy and Housing Elements Developers can propose projects that ignore local zoning, and the city often has no legal basis to refuse. Letting the no net loss inventory erode is one way to lose compliance, and several California jurisdictions have already seen builder’s remedy applications land as a result.
Keeping Compliance Running Through the Cycle
The no net loss duty runs for the entire planning period, typically eight years. The inventory has to stay adequate every day of that cycle, not just at adoption.2California Department of Housing and Community Development. SB 166: No Net Loss Law For planning staff, that means every residential application needs a quick check against the housing element inventory. If the proposed unit count or income mix diverges from what the inventory assumed, the written findings process has to run before approval, and the 180-day clock starts if the remaining sites cannot absorb the loss. Jurisdictions that bake the check into their standard development review rarely get caught short. Those that treat it as an afterthought tend to find out from HCD or a housing advocate, when the political and legal costs are much higher.