In Pima County, most residential properties are valued using the Market Approach. In this approach, value is estimated by comparing sales and adjusting them for differences in characteristics to indicate a value for the subject property. In a single-property appraisal, typically 3-5 comparables are used to determine a value for the subject property.
For ad valorem purposes, single-property appraisal is not an efficient method due to the large number of properties, which must be valued each year. Therefore, the Assessor's office determines values using Mass Appraisal. By utilizing a computer-assisted mass appraisal system (CAMA) to assist us in this process, annual values on residential properties can be established uniformly and at a relatively low cost.
Arizona Department of Revenue Publication 546
IAAO Standard on Mass Appraisal of Real Property
IAAO Standard on Automated Valuation Models (AVMs)
Mass Appraisal Overview
Mass appraisal is the process of establishing values on groups of properties as of a given date using standardized procedures and statistical testing. Its purpose is the equitable and efficient appraisal of property for ad valorem purposes. The process involves data collection, market analysis, and quality control.
An important aspect of mass appraisal is the collection of data on economic and neighborhood trends. Of particular interest is the identification of economic areas economic districts and neighborhoods to account for location differences in the market. For maps of these areas, see our Residential Economic Area Maps below.
Data is collected on physical and location characteristics, which can assist in the valuation and identification process. Not all data collected may be used in the valuation process. Most characteristics area obtained by on-site inspections when the property is newly constructed and thereafter at periodic stages of activity. Characteristics may also be collected through use of mail questionnaires, aerial photography, and information from other outside sources. To see the physical characteristics of your property review the Residential Model Characteristics page through the parcel information page.
For residential properties, a typical time period of 36 to 48 months (3 to 4 years) of sales data is collected and analyzed each year in preparation of values. These sales must first be adjusted to the end of the data collection period, generally June of the year proceeding the valuation year. These adjustments for time account for the principle of supply and demand as well as the principle of change.
Market Analysis and Valuation
After the necessary data has been collected and categorized, values are determined using a technique called Multiple Regression Analysis. Multiple regression explores and quantifies the relationship between two or more components of known and available data (sales prices and property characteristics) to predict a value. This process analyzes the sales and characteristic data to develop appropriate adjustments for amenities found to be meaningful in the marketplace, such as square footage, pools, garages, etc. These adjustments can then be applied to all properties in a fair and consistent manner.
To measure quality in a mass appraisal setting, statistical tests are utilized. A sales ratio study is one such test and is the final step in the mass appraisal process. Properties, which have sold, are grouped and the established values are compared to the sale amounts to ensure that they fall within an acceptable range.
Residential valuation information on change in value as well as level of value to market. The information is shown by sale year/economic district.
Tax Year 2017 Data:
Tax Year 2016 Data:
Tax Year 2015 Data:
Tax Year 2014 Data:
Tax Year 2013 Data:
Residential Frequently Asked Questions
Why did my value increase at a level different from others in my area?
There are numerous scenarios, which would affect the percent of increase from one year to the next on residential properties. In addition, this comparison is not a standard method or technique employed in the valuation process. Therefore, the focus should be on the current value, to see if it reflects market and whether it is valued fairly in comparison with similar properties.
My full cash value decreased but the limited increased – why?
In Pima County, most residential properties are valued on an annual basis using the market approach. One of the larger influences in the market (recorded sales) is location. Different geographic areas of Tucson experience different market trends and the values are adjusted accordingly. While the full cash value is determined using the market approach, limited values are calculated according to a mathematical formula pursuant to Arizona Revised Statues, A.R.S. § 42-13301 and A.R.S. § 42-13302.
I don't intend to sell my house, so why should my value be based on market?
The State of Arizona has an ad valorem tax system. An ad valorem tax is based on the principal that the amount of tax paid should depend on the value of property owned.
Why should I be penalized for somebody else paying a high price for a home in my neighborhood?
It isn't a penalty. If a number of homes similar to yours are selling for more, it increases the marketability and market value of your property.
The condition of my property is getting worse each year. It needs paint and I would have to do a lot of work to sell it or it would not sell for the same price as other properties that didn't need work.
Items of this nature are referred to as "Deferred Maintenance" and are the responsibility of the owner to maintain. The Assessor's Office takes a neutral position on this issue for the following reasons:
- The condition of the property often changes from year to year and the Assessor's Office does not re-canvas to identify these changes.
- The Assessor's Office cannot reward property owners with a reduction in value for their lack of maintaining their home, just as it cannot punish property owners with higher values for maintaining their home.
How can my property's value increase when I haven't done anything to improve it?
Property values are based on the activity in the marketplace. Therefore, the most frequent cause of a change in valuation is change in the market or economy. If a certain neighborhood or community becomes a fashionable place to live, the change in valuation will be reflected by the prices paid for property. In a stable neighborhood, with no extraordinary pressure from the market, simple inflation may increase property value.
There are properties in my area with additions that the Assessor's Office hasn't picked up. My neighbors aren't paying their fair share. Because of this, my value should be lower.
The Assessor's Office will be happy to collect the necessary information and verify the listing information for those properties. However, this does not prove that your value is incorrect or that it should be altered.
The houses that sell in my area far exceed the house that I have and they have been remodeled. How can you compare my house with those?
We make an effort to identify properties of this nature and field check them to verify their listing information. Because we're working within a range of selling prices, one or two sales, which may have incorrect listing information, would not affect the value of your home. We could even eliminate them from our analysis and see if the value is supported by other sales in the area. If you would like to identify the properties, we can initiate field inspections on them.
I built my own home. It cost a lot less to build it than the value that you have placed on it.
Labor costs, material costs and the market value of the land are all factors associated with the cost to build your home. Even though one has built their own home, their house will sell on the market at the same level as other houses in the area built by contractors. The difference in value between what the property cost to build and what it would sell for is called "sweat equity". Therefore, the value assigned by the Assessor's Office is what the market indicates by utilizing a comparative sales approach.
I have an older home in an area where they are building new homes. How will this affect my property value?
In the valuation process, adjustments are made for age, type of construction as well as a number of other variables.
How can my property increase in value if it is getting older?
In order to establish a market value for your property we must analyze the market in your neighborhood. If homes, with similar characteristics such as age, in your area are selling for a higher price, then it would suggest that your property would be worth a similar amount.
What if I think the Assessor's value is wrong?
If you feel the Assessor has made a mistake in valuing your property, you may file a petition for review with the Assessor's office. The an overview of the process is on our Appeals Process page. You may also review our Residential Valuation Review Workbook to assist you in reviewing your property's assessment.
There are no paved streets in my area. I don't have trash pickup or other services. Therefore, my value should be lower.
Sales of properties in the same local would reflect the same conditions and therefore establish market and value. The lack of services needs to be directed to those specific agencies and cannot be addressed by the Assessor's Office.