Assessor

Homeowners, business owners, and renters in Maricopa County often hear about the “Assessor” when property value notices or tax bills show up, but it is not always clear what this office really does—or how to use its tools to your advantage. This article walks through how the Maricopa County AZ Assessor operates, what services the office provides, how property values are determined, what to do if you disagree with a valuation, and which programs might help reduce your tax burden. You’ll also see how to use official online tools to look up parcels, register rentals, and get help when you need it.

Get to know the Maricopa County Assessor and why this office matters

The Maricopa County Assessor is the elected official responsible for valuing more than a million real and personal property parcels across the county each year. The position is currently held by Eddie Cook, who brought decades of technology and leadership experience into the role and emphasizes a “One Team” culture focused on fairness, equity, and efficient service for taxpayers.

On the official county assessor page, you can read more about his background in engineering, high-tech industry leadership, and local government, including his time on the Gilbert Town Council. That mix of public and private experience shapes how the office uses new technology, data, and process improvements to keep valuations as accurate and transparent as possible.

The assessor’s job affects every property owner because the values determined by this office are used to calculate property taxes. While the assessor does not set tax rates or send tax bills, fair and accurate valuation is the first step in making sure everyone pays only their appropriate share.

Understand what the Maricopa County Assessor actually does (and does not do)

A lot of confusion comes from mixing up the roles of different county offices. Here’s what the Maricopa County Assessor’s Office is responsible for, and what falls to other departments.

Core duties of the Assessor

The office has several core responsibilities:

Locate and identify all taxable property in Maricopa County

Determine the value of each property using standardized appraisal methods

Classify property according to its use (residential, rental, commercial, agricultural, etc.)

Maintain the assessment roll, which is the official list of parcels, owners, values, and classifications

Apply legal exemptions and valuation relief when property owners qualify

The office handles both real property (land and buildings) and a wide range of personal property tied to businesses and mobile homes. In a recent year, the office noticed and administered more than 1.7 million parcels and accounts with full cash value in the hundreds of billions of dollars.

What the Assessor does not handle

Just as important is what the Maricopa County Assessor does not do:

The office does not compute or collect property tax bills. That is handled by the county treasurer.

It does not set tax rates or create tax law. Tax policies come from state statutes and local governing bodies.

It does not conduct property line surveys or provide legal advice on transferring ownership.

It does not control zoning or building permits—those functions belong to county or city planning departments.

If you have questions about the accuracy of your property value, classification, or exemptions, the Assessor is the right place. If a question involves how much you owe, payment issues, or tax liens, you will ultimately work with the treasurer after you understand your valuation.

See how the Assessor’s Office is organized behind the scenes

To manage so many parcels and programs, the Maricopa County Assessor’s Office is structured into several divisions, each focused on a key area of service. The overall structure and mission are outlined in the About Us section.

Administrative Division

This division supports the people and systems that keep everything running. It handles:

Budgeting and procurement
Human resources and hiring
Legislative bill tracking and intergovernmental coordination
Data sales and special districts support

The goal is to give the rest of the office the tools and direction needed to deliver accurate valuations and responsive service.

Valuation Relief Program Division

Many residents interact with this division when they need help with exemptions or relief programs. It includes:

Personal Exemptions – Senior valuation protection, widows/widowers, and disability exemptions

Organizational Exemptions – Historic, religious, government, and other qualifying nonprofit property

Public Assistance – Front-line staff who help property owners understand applications, eligibility, and deadlines

This division keeps programs in line with Arizona law and helps residents navigate the documentation required to qualify.

Information Technology Division

The office’s reliance on data and mapping makes technology crucial. The IT division:

Manages applications, databases, and servers
Oversees the public-facing website and online services
Develops and maintains GIS (mapping) systems
Supports the Maricopa Assessment Replacement System (MARS), a modern system for valuations

This division is a big part of how the office provides map tools, parcel details, and online filing options to the public.

Property Ownership & Mapping Division

This team keeps ownership records and maps current by:

Updating ownership and title information when deeds are recorded

Maintaining the county’s parcel fabric—the detailed map of every parcel

Producing custom maps and supporting customer requests involving boundaries or ownership changes

If you recently bought, sold, or split property, this division is involved in recording the change on the assessment roll.

Appraisal Division

This is where property values are determined. The Appraisal Division:

Discovers, lists, and values residential, commercial, agricultural, and personal property

Uses mass appraisal models that comply with state standards

Reviews building permits, parcel splits and combinations, recheck requests, and notices of claim

Handles administrative appeals and supports cases that reach the courts

The division also oversees business personal property accounts and audits to ensure fair reporting and valuation for equipment and other taxable personal property.

Use the Assessor’s online tools to research your property

Most residents first interact with the Maricopa County Assessor online, whether to search for a parcel, check a valuation, or confirm ownership details.

Look up parcel and ownership information

On the main website, you can search for a property by:

Parcel (APN) number
Owner name
Street address
Subdivision name or MCR number
City, ZIP code, or Section–Township–Range

For mobile homes or business accounts, searches can be done by account number or VIN (for mobile homes). This flexibility makes it easier to find a property even if you only know part of the information.

Explore interactive maps and spatial data

If you want a map view, the Assessor maintains an online Parcel Viewer where you can:

See parcel boundaries and nearby properties
Generate basic mailing lists by creating a buffer around a point of interest
Print or export map views for your records

These mapping tools connect to GIS data maintained by the county, giving you a clearer picture of how your property fits into the surrounding area.

Find quick answers in the FAQ and “How Do I” sections

Many common questions—such as how to print all valuation years, change your mailing address, sign up for e-notices, or register a rental—are covered in detail in the Assessor’s online help and FAQ resources. You can browse the comprehensive Frequently Asked Questions by category or search for specific topics like agriculture, property values, ownership changes, or valuation relief.

Learn how your property is valued in Maricopa County

Understanding how the Maricopa County AZ Assessor assigns value to your property helps you read your notice more confidently and decide whether an appeal is appropriate.

Full cash value vs. limited property value

Two values appear on your notice:

Full Cash Value (FCV) – This is meant to approximate market value using mass appraisal methods, except where special statutory formulas apply. It reflects the value of land plus improvements.

Limited Property Value (LPV) – This is a statutory value designed to limit large jumps in taxable value. Under Arizona law and voter-approved Proposition 117, LPV increases are generally capped at 5% per year, unless there are certain qualifying changes like new construction, omissions, or major remodeling.

For most real property, tax rates are applied to the LPV, not the FCV, even when market values fluctuate. However, the LPV can never exceed the FCV.

Legal class and assessment ratio

Each parcel is assigned a legal class based on how it is used:

Primary residence
Residential rental or non-primary residential
Commercial
Agricultural
Historic or specialized property types

The legal class determines the assessment ratio, which is the percentage of value used to calculate the assessed value. Different classes have different ratios set by state law, and a single parcel can have mixed use and multiple classes if it serves more than one purpose.

Mass appraisal and why values differ between neighbors

To handle over a million parcels, the Assessor uses mass appraisal models that rely on:

Recent sales data
Neighborhood trends
Property characteristics such as square footage, lot size, quality, and improvements

Even when homes look similar, differences in features, additions, or data on file can result in different values. That is why reviewing your valuation notice and the property’s characteristics is important; if something is wrong or missing, you have a right to ask for a correction or appeal.

Read your Valuation Notice and know your appeal options

Each year, property owners receive a Valuation Notice from the Maricopa County Assessor. This is not a tax bill—it is advance notice of the values the treasurer will later use to calculate taxes.

What your Valuation Notice includes

The notice typically shows:

Full cash value and limited property value for the upcoming tax year
Legal classification
Assessment ratio
Assessed value
Prior year values for comparison
Appeal instructions and deadlines

The Assessor is required by law to send this notice well before taxes are billed so owners have time to review and respond.

When and how to appeal your valuation

If you believe your property value is too high or your legal class is wrong, you can:

File an administrative appeal with the Assessor’s Office within the statutory deadline (generally 60 days from the date on the notice).

Provide evidence such as recent sales of comparable properties, documentation of physical problems with your property, or proof regarding usage or occupancy.

If you disagree with the Assessor’s decision, you may have the option to appeal further to the State Board of Equalization or the courts, depending on the type of property and stage of appeal.

Detailed steps and options are outlined on the appeals page, including information on what to do if you discover an error or need to file a notice of claim.

Take advantage of valuation relief and exemption programs

For many residents, especially seniors and people with limited income or disabilities, valuation relief can make a significant difference.

Senior Valuation Protection and personal exemptions

The Assessor administers several programs, including:

Senior Valuation Protection – A program that can “freeze” the limited property value for qualifying seniors who meet age, residency, and income requirements, helping protect them from large future increases.

Widow, widower, and disability exemptions – Partial exemptions applied to the assessed limited property value of real property or, if applicable, a mobile home or automobile, based on documentation of status and income.

Disabled veteran exemptions – Reductions based on the percentage of disability and ownership interest.

Each program has specific eligibility rules, required forms, and strict filing windows, often between January 1 and September 1. Income documentation is usually required, and some programs require periodic renewal.

You can review eligibility rules, application forms, and important deadlines on the official valuation relief programs page.

Know how different property types are handled by the Assessor

The Maricopa County Assessor’s Office manages more than standard single-family homes. Understanding how different property types are treated can help you avoid surprises.

Residential and rental property

Residential property is classified based on how it is used:

Primary residence – Your single main home, or one occupied by a qualified family member; eligible for certain credits and treated differently than rentals.

Residential rental – Property used solely as leased or rented housing must be registered as a rental with the Assessor and may fall into a different legal class.

If you own a rental, you are required by state law to register it with the Assessor. You can do this online by searching your parcel and following the prompts to register the property as a rental. If a property is misclassified—for example, treated as a primary residence when it’s actually a rental—state law allows penalties and reclassification.

Business personal property

Businesses are taxed not just on real estate but also on certain equipment and personal property used in operations. The Assessor:

Requires annual reporting of business personal property assets

Values equipment using original cost and age, applying depreciation according to state guidelines

Applies statutory exemptions for eligible business property up to a certain value threshold

Businesses receive annual personal property statements and must report additions, deletions, and changes by deadline. Failure to file can result in penalties and estimated valuations.

Agricultural and special-use property

Agricultural classification is available for properties that operate as genuine commercial agricultural businesses, with a reasonable expectation of profit and use consistent with state law. The Assessor:

Reviews applications and supporting documentation
Periodically canvasses and inspects properties to verify use
May remove agricultural classification if statutory criteria are no longer met

Not all rural or equine activities qualify as agricultural; some uses, like rodeo events or trail riding, may be treated as commercial rather than agricultural under state law.

Mobile and manufactured homes

Mobile and manufactured homes are valued differently depending on whether they are:

Affixed to real property, in which case the structure is tied into the parcel’s overall value but still depreciated using mobile home guidelines; or

Assessed as personal property, where valuation is based on factory list price and depreciation schedules.

Moving a mobile or manufactured home generally requires a special permit, and the Assessor verifies that taxes are paid and records are updated when a unit changes locations or owners.

Use “How Do I” help to complete common tasks

The Assessor’s “How Do I” resources are built around the most frequent questions from residents. From this section of the site, you can:

Learn how to print all valuation years for your property
Update your mailing address
Register or cancel a rental registration
Sign up for electronic notices
Request data or public records
Enlarge sketches for printing
Update your legal class during certain timeframes

These guides are especially helpful if you are completing a process for the first time and want to make sure you follow the steps correctly and meet all deadlines.

Understand which office to contact for taxes, deeds, or valuations

Because several county departments are involved in property-related issues, it helps to know which office handles what.

When to contact the Assessor

Contact the Maricopa County Assessor’s Office if you need help with:

Questions about your property value or classification
Appealing a valuation or filing a notice of claim
Exemption and valuation relief applications
Rental registration or removing a rental designation
Ownership data and parcel details shown on the Assessor’s website

You can use the secure online form on the contact the Assessor’s Office page if you prefer not to call or visit in person.

When to contact the Treasurer or Recorder instead

Some property questions belong to other offices:

For property tax bills, payment methods, delinquent taxes, tax liens, and detailed billing questions, visit the Maricopa County Treasurer’s Office website.

For recording deeds, checking recorded documents, or questions about how a deed was written, the proper office is the Maricopa County Recorder’s Office.

The Assessor’s Office relies on recorded documents from the Recorder to update ownership and then provides values used by the Treasurer to calculate tax bills. Knowing where you are in that chain makes it easier to get answers quickly.

Tap into official reports, data, and mapping tools when you need more detail

For professionals, homeowner associations, or residents who need more than basic parcel information, the Assessor offers:

Reports and data sales – Bulk data for organizations that need large datasets, often with the help of internal IT staff integrating with the Assessor’s API.

Mapping exports – Ability to print or export custom maps from the parcel viewer for use in presentations, mailings, or planning.

Public records support – Processes for submitting data or records requests when standard lookup tools are not sufficient.

Using these official channels is the best way to get accurate, up-to-date data that matches what is on the county’s assessment roll.

Assessor-related departments and offices (addresses and phone numbers)

Maricopa County Assessor’s Office – 301 W Jefferson Street, Phoenix, AZ 85003 – Phone: 602-506-3406

Maricopa County Assessor FAQs

How do I look up my parcel and property information online?

You can search your parcel, ownership, and property characteristics using the Assessor’s online mapping tools. Start with the Parcel Viewer, where you can search by parcel number (APN), owner name, address, subdivision, city, or ZIP, then zoom in to see parcel boundaries, aerial imagery, and links back to detailed Assessor records. The Parcel Viewer also lets you create buffers and export mailing lists of nearby owners as a CSV file, which is handy for notices to neighbors. Access it through the county’s Parcel Viewer maps site at Parcel Viewer maps site.

How can I appeal my property valuation or correct an error?

If you believe your property value or classification is wrong, you can use the Assessor’s appeals process. For current-year valuation notices, you generally have 60 days from the mailing date on your notice to file a Petition for Review. For factual errors or misclassifications discovered later (for example, wrong square footage or incorrect legal class), you may file a Notice of Claim, which can sometimes correct up to three prior tax years if an error is confirmed. Detailed instructions, forms, and the online appeal tutorial are available on the Assessor’s appeals page.

Where do I find my tax bill and current tax rates?

The Assessor sets property values but does not calculate or collect property taxes. Tax bills, payment options, and tax lien information come from the Maricopa County Treasurer. You can look up your tax bill, see prior-year payments, and review tax-lien details through the Maricopa County Treasurer’s Office website. If you want to understand how your tax rate is built—by school districts, cities, special districts, and countywide districts—review the county’s official Tax Levy and Rates page, which publishes all current and historical levies and rates back to 2000.

What relief or exemption programs are available for homeowners?

The Assessor administers several valuation relief and exemption programs designed to ease the tax burden for qualifying residents. These include Personal Exemptions for widows, widowers, totally disabled individuals, and disabled veterans, as well as the Senior Valuation Protection program, which can “freeze” the limited property value for eligible seniors who meet age, residency, and income requirements within set filing windows each year. Applications often require proof of age, residency, disability status (where applicable), and income documentation for all owners. Program descriptions, current income limits, filing deadlines, and online application options are outlined on the Assessor’s valuation relief programs page.