Unincorporated Maricopa County Bonds, Assurances and Permit Insurance

The Maricopa County Subdivision Regulations, adopted in 1990 and revised October 23, 2024, and again January 9, 2026, to update references after the Zoning Ordinance update approved December 10, 2025, state that an assurance shall be provided before approval of any plat. It secures street, sewer, drainage and flood control improvements, and the County may also require it for utilities and for restoring disturbed ground. Maricopa County must be named as beneficiary, an assurance in the form of an agreement must be recorded and the plat must state that the assurance meets A.R.S. 11-821 and 11-822.

Section 303 sets no percentage. The owner or subdivider provides an engineer's cost estimate, and the County determines the final amount. Release starts with a written request to the subdivision coordinator, after which Planning and Development and MCDOT make recommendations. The accepted forms, each at the County's discretion and subject to County Attorney approval, are:

• Cash or a certified check
• A performance bond from a surety licensed in Arizona
• Certificates of deposit, Treasury bills or other securities backed by the United States
• Money or negotiable bonds held by an escrow agent or trust company
• An unexpirable irrevocable letter of credit in favor of the County from a third-party financial institution
• A third-party trust agreement, which bars lot transfers until the improvements are accepted and can replace an existing assurance only where no lots have been sold
• Another form the Director considers appropriate in consultation with the County Engineer

MCDOT posts a Performance Surety Bond form that shows no date, so ask the County which version it currently accepts before the surety prepares the bond. The form limits the surety's obligation to no more than 120 percent of the cost of the improvements, based on a licensed professional engineer's estimate the County has accepted. Scope changes keep the surety bound up to 120 percent of the original estimate; above that, the principal must obtain a rider.

The 120 percent figure is a ceiling written into the bond form, not a percentage the Subdivision Regulations require. The form also says the bond cannot be canceled until the Board of Supervisors accepts the improvements or the County authorizes release in writing, that the County may declare default on 30 days' written notice and that the surety may finish the work or settle in money. The bond does not satisfy the obligation until the County accepts and approves it, so the indemnity and collateral terms typically need to be settled well before the plat hearing.

MCDOT requires a permit for all work within its right-of-way and states that a performance bond is required to provide financial assurance to the County, with non-cash bonds pre-approved by the County Attorney's Office. Ordinance P-36 prints no adoption date, so confirm the current version with MCDOT Permits and Records. Its assurance must be not less than 100 percent of an engineer's construction cost estimate, with a $250 minimum, and may take the form of cash, letters of credit, a bond or another promise or pledge. A lapsed assurance can lead to a Cease Work Order.

For assurances required by A.R.S. 11-822 on subdivision work, release waits for final approval and a warranty assurance of 10 percent of the original assurance, held for one year, with any balance released at the end of that year. Exemptions include public agencies, public service corporations with net worth over $1,000,000, resident owners doing their own work and driveway or building-permit work of $5,000 or less when final drainage clearance or occupancy is held until the right-of-way work is done.

The insurance terms ask for primary liability and property damage insurance from an Arizona-authorized carrier insuring the permittee and the County, at minimums of $1,000,000 for injury to one person in one accident, $2,000,000 for more than one person and $1,000,000 for property damage, with Maricopa County named as additional insured. The permittee indemnifies the County, including for claims alleging joint negligence. A permit runs six months or until the insurance expiration date, whichever is shorter. A lapse in insurance invalidates it, so a policy renewing mid-project can cut a permit short.

The Air Quality Department says Rule 310 requires a dust control permit for any activity that disturbs 0.1 acre (4,356 square feet) or more, along with a dust control plan. On a subdivision or utility job, the permit holder and the grading contractor should agree in writing who holds the permit, who runs water trucks and who answers a notice of violation. Fines and penalties are often outside what a liability policy can respond to, subject to the policy terms.

The Flood Control District of Maricopa County requires a Floodplain Use Permit before building, grading or filling in a designated floodplain, even where no building permit is needed. Floodplain work can change the drainage and flood control improvements the subdivision assurance secures, and it raises questions about storm damage during construction and runoff onto neighboring land.

The Subdivision Regulations require a 100-year assured water supply for all subdivision lots within an Active Management Area. Under A.R.S. 45-576, a subdivider in an Active Management Area must obtain a certificate of assured water supply from the director of the Arizona Department of Water Resources before presenting the plat for approval, unless it has a written commitment of service from a designated provider, and the supply must meet the need for at least one hundred years.

Because the certificate comes before the plat and the assurance comes before plat approval, water timing can hold the surety request, the lender's draw schedule and builders risk inception dates in place. A developer weighing an unincorporated site against a nearby city site should confirm the water path with the County and the provider before committing surety capacity.