# Unincorporated Maricopa County Bonds, Assurances and Permit Insurance

URL: https://mycontractorsinsurancequote.com/arizona/metros/phoenix/maricopa-county
Updated: 2026-10-29 · Reviewed by the Principal, Gleason Insurance Brokers, LLC
Publisher: My Contractors Insurance Quote, a website of Gleason Insurance Brokers, LLC

In unincorporated Maricopa County, a subdivider must post an assurance naming the County as beneficiary before any plat is approved, in an amount the County sets from the engineer's cost estimate rather than a fixed percentage. Work in County right-of-way adds a permit bond of at least 100 percent of the engineer's estimate, a 10 percent one-year warranty assurance on subdivision work and liability insurance naming the County as additional insured, with the permit ending when that insurance expires. Dust, floodplain and assured water supply rules can shape the schedule before any of those instruments is released.

## Key Decision Points
- The County's Subdivision Regulations, revised January 9, 2026, require an assurance before plat approval, with Maricopa County named as beneficiary.
- The regulations set no percentage; the County determines the amount from the owner's engineer's cost estimate.
- The MCDOT performance surety bond form caps the surety's obligation at 120 percent of the accepted estimate, and the form carries no date.
- Right-of-way Ordinance P-36 calls for a 10 percent warranty assurance held one year on assurances required by A.R.S. 11-822.
- A right-of-way permit runs six months or until the insurance expiration date, whichever is shorter.
- Cities such as Buckeye, Goodyear, Mesa, Surprise, Peoria and Gilbert set their own bond and permit rules.

## Which Rules Apply in Unincorporated Maricopa County

This page covers land outside city and town limits, where the County's Planning and Development Department, the Maricopa County Department of Transportation (MCDOT), the Air Quality Department and the Flood Control District set the requirements. Incorporated cities such as Buckeye, Goodyear, Mesa, Surprise, Peoria and Gilbert adopt their own engineering standards, bond amounts and warranty terms, so a site a mile across a city boundary can carry a different security package. Confirm the jurisdiction from the parcel record before the surety is asked for a bond.

Growth is one reason the distinction matters. MCDOT's Transportation System Plan 2050 baseline sheet projects unincorporated population rising to about 281,000 by 2050, a 49.5 percent increase, from a base of about 188,000; the sheet labels that base both 2023 and 2025, so treat the starting year as unclear. It names Anthem, Wittmann, Dove Valley and Tonopah as the areas with the largest expected increases and ties growth to the SR 74 extension, SR 30, I-11 and the SR 303L extension.

For a comparison with a city that sets fixed percentages, see [Goodyear's performance and warranty bond rules](https://mycontractorsinsurancequote.com/arizona/metros/phoenix/goodyear).

## Subdivision Assurance Before Plat Approval

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

Statewide rules and how sureties underwrite them are explained in [Arizona subdivision assurance bonds](https://mycontractorsinsurancequote.com/construction-surety-bonds/subdivision-improvement-bonds/arizona).

### Illustrative scenario: A Tonopah Plat and a Permit That Ended Early

Saguaro Flats Land Co. (fictional) plans 240 lots on unincorporated land near Tonopah. Its engineer estimates the street, drainage and flood control improvements at $9.2 million, and the County sets the subdivision assurance from that estimate, with the County as beneficiary, before the plat goes forward. The developer's surety issues a performance bond on the MCDOT form, capped at 120 percent of the accepted estimate, and a scope change later pushes costs past that cap, so the surety adds a rider. Midway through the right-of-way work, the grading contractor's liability policy reaches its expiration date three months into a six-month permit, and the permit ends with it under P-36. Renewal paperwork naming the County as additional insured is filed, and a new permit is issued after a two-week pause. At acceptance, the developer posts a 10 percent warranty assurance held one year. These details are hypothetical, and a real program depends on the agency, the surety or carriers and the firm's own risk.

## The MCDOT Performance Bond Form and Its 120 Percent Cap

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.

Capacity and indemnity questions for a subdivider are discussed under [Arizona developer surety and insurance planning](https://mycontractorsinsurancequote.com/arizona/audiences/developers).

## Right-of-Way Ordinance P-36: Bond, Warranty and Insurance

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.

Permit bond practice across the state is compared in [Arizona right-of-way permit bonds](https://mycontractorsinsurancequote.com/construction-surety-bonds/encroachment-permit-bonds/arizona).

## Dust Control and Floodplain Use Permits

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.

Dust, sediment and runoff exposures are discussed with [pollution liability for site development](https://mycontractorsinsurancequote.com/contractors-pollution-liability-insurance/site-development).

## Assured Water Supply in Active Management Areas

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.

West Valley sites inside city limits follow local rules, as with [Buckeye developer bond requirements](https://mycontractorsinsurancequote.com/arizona/metros/phoenix/buckeye).

## Before You Ask for a Quote

### What to Gather
- Parcel record confirming the site is outside city and town limits
- Engineer's cost estimate for street, sewer, drainage and flood control improvements
- Certificate of assured water supply or a designated provider's written commitment
- Current MCDOT bond form and the surety's approved bond line and indemnity terms
- Certificates of insurance naming Maricopa County as additional insured, with expiration dates
- Rule 310 dust control permit and dust control plan
- Floodplain maps and any Floodplain Use Permit for the site

### What to Ask the Insurer or Surety
- What amount will the County set for the subdivision assurance from our estimate?
- Which assurance form fits our lending and lot-sale plan: bond, letter of credit or trust agreement?
- Does the current MCDOT bond form match the version our surety has?
- Do our policies expire before the right-of-way permit work is finished?
- Who holds the dust control permit, and who pays a penalty?
- How long will the 10 percent warranty assurance tie up surety capacity?

## Broker Notes

**Quick Answer:** Unincorporated Maricopa County requires a subdivision assurance naming the County as beneficiary before plat approval, sized by the County from the engineer's estimate. Right-of-way work adds a bond of at least 100 percent of the estimate, a 10 percent one-year warranty assurance on subdivision work and insurance naming the County as additional insured.

**Common Mistake:** Treating the 120 percent figure on the MCDOT bond form as the required assurance amount, or letting a liability policy expire mid-permit, which ends the right-of-way permit under P-36.

**Broker Perspective:** We typically line up the surety's capacity with the County's assurance amount early, match policy expiration dates to permit terms and confirm with the County which bond form version it currently accepts.

**Coverage Impact:** Surety credit stays committed until the County accepts the improvements and the one-year warranty assurance ends. Additional insured, primary wording and indemnity terms in P-36 can vary in how they fit a given policy, subject to underwriting and the terms of the policies issued.

## Questions Buyers Ask

### What percentage does Maricopa County require for a subdivision assurance?

The Subdivision Regulations set no percentage. The owner or subdivider provides an engineer's cost estimate, and the County determines the final amount. The 120 percent figure on the MCDOT bond form is a cap on the surety's obligation, not a required amount. Confirm the current requirement with the County.

### Can a letter of credit replace a bond for a Maricopa County plat?

The regulations list an unexpirable irrevocable letter of credit from a third-party financial institution in favor of the County as one accepted form, alongside cash, surety bonds, securities, escrowed funds and trust agreements. Each form is at the County's discretion and needs County Attorney approval.

### How long is the warranty assurance on County right-of-way work?

Under Ordinance P-36, for assurances required by A.R.S. 11-822, release waits for final approval and a warranty assurance of 10 percent of the original assurance, held for one year. Any balance is released at the end of that year.

### Why would a right-of-way permit end early?

P-36 issues a permit for six months or until the insurance expiration date, whichever is shorter. A lapse in insurance invalidates the permit. Matching renewal dates to the work schedule can help avoid a stop.

### Do these County rules apply inside Surprise, Peoria or Gilbert?

No. Incorporated cities such as Surprise, Peoria, Gilbert, Goodyear, Buckeye and Mesa set their own subdivision, bond and permit rules. The County rules on this page apply to unincorporated land; confirm the jurisdiction for each parcel.

## Official Sources

1. [Maricopa County Subdivision Regulations (revised January 9, 2026)](https://www.wrr.maricopa.gov/Archive.aspx?ADID=6308), Maricopa County Planning and Development Department. Revision dates; Sec. 203 assurance before plat approval, County as beneficiary, recorded agreement, accepted forms and release request; Sec. 303 engineer's cost estimate with amount set by the County; 100-year assured water supply in Active Management Areas; plat statement citing A.R.S. 11-821 and 11-822. Verified 2026-10-26.
2. [Maricopa County Ordinance P-36, Requirements for Permits to Work in Right-of-Way](https://www.maricopa.gov/DocumentCenter/View/94056/Requirements-to-Work-in-ROW-P-36), MCDOT Permits and Records Division. Art. X assurance of at least 100 percent of the engineer's estimate, $250 minimum, forms, exemptions, Cease Work Order, 10 percent one-year warranty assurance; Art. XI primary insurance, limits, County as additional insured, indemnity, six-month permit term tied to insurance expiration. No adoption date printed. Verified 2026-10-26.
3. [MCDOT Performance Surety Bond form](https://www.maricopa.gov/DocumentCenter/View/98795/MCDOT-Performance-Surety-Bond), Maricopa County Department of Transportation. 120 percent cap on the accepted engineer's estimate, rider above the cap, non-cancellable until acceptance or written release, 30-day default notice, Arizona-licensed surety, acceptance by the County. The form shows no date. Verified 2026-10-26.
4. [MCDOT Permits](https://www.maricopa.gov/769/Permits), Maricopa County Department of Transportation. Permits required for all work in County right-of-way; performance bond required; non-cash bonds pre-approved by the County Attorney's Office. Verified 2026-10-26.
5. [Do I Need an Air Permit?](https://www.maricopa.gov/2274/Do-I-Need-an-Air-Permit), Maricopa County Air Quality Department. Rule 310 dust control permit for disturbing 0.1 acre (4,356 square feet) or more, plus a dust control plan. Verified 2026-10-26.
6. [Flood Control District of Maricopa County, Permits](https://www.maricopa.gov/5657/Permits), Flood Control District of Maricopa County. Floodplain Use Permit required before building, grading or filling in a designated floodplain, even where no building permit is required. Verified 2026-10-26.
7. [A.R.S. 45-576, Certificate of assured water supply](https://www.azleg.gov/ars/45/00576.htm), Arizona State Legislature. Certificate of assured water supply before presenting a plat in an Active Management Area unless a designated provider commits in writing; supply for at least one hundred years. Verified 2026-10-26.
8. [A.R.S. 11-822, County subdivision plat approval and assurances](https://www.azleg.gov/ars/11/00822.htm), Arizona State Legislature. Plat approval includes specific identification and approval of the assurances. Verified 2026-10-26.
9. [MCDOT Transportation System Plan 2050, Population Growth sheet](https://fcd.maricopa.gov/DocumentCenter/View/122966/MCDOT-TSP2050_04-Population-Growth), Maricopa County Department of Transportation. Unincorporated population about 188,000 to 281,000 by 2050 (49.5 percent; base year labeled both 2023 and 2025); growth near Anthem, Wittmann, Dove Valley and Tonopah; SR 74, SR 30, I-11 and SR 303L. Verified 2026-10-26.

## Related Decisions

- [Phoenix-area agency bond and insurance rules](https://mycontractorsinsurancequote.com/arizona/metros/phoenix)
- [Arizona civil and infrastructure contractor insurance](https://mycontractorsinsurancequote.com/arizona/audiences/civil-infrastructure-contractors)
- [Goodyear performance and warranty bonds](https://mycontractorsinsurancequote.com/arizona/metros/phoenix/goodyear)
- [maintenance and warranty bond terms](https://mycontractorsinsurancequote.com/construction-surety-bonds/maintenance-warranty-bonds)
- [land developer insurance and bonds](https://mycontractorsinsurancequote.com/who-we-serve/developers-subdividers/land-developers)

---

Start a quote request: https://mycontractorsinsurancequote.com/get-a-quote · Call 844-978-7283

Contract and insurance reviews are a courtesy service that may be available at times, depending on our workload and on the size, timing and complexity of the project. A review is not guaranteed and is limited to insurance considerations. It is not legal advice and is not a substitute for advice from your own legal counsel, which you may need before signing a contract or obtaining coverage.

Insurance and surety services are provided through Gleason Insurance Brokers, LLC. Site information is educational and does not constitute legal advice, a binder, an offer of coverage, a guarantee of eligibility or confirmation of policy terms. Insurance conditions are governed by actual issued policies; surety rights and obligations are governed by bond and indemnity documents.