Estimating Additional Taxes
Multnomah County is unable to provide an estimate of what future property taxes will be for a tax year that has not been certified.
The potential increase in the amount of future property taxes associated with a variety of property events - such as (but not limited to) newly platted or newly created properties, new construction, additions, remodeling, renovation or rehabilitation - cannot be provided before the changes to the property have been valued by the Assessor’s Office, nor before the future tax year’s calculation components are certified. The tax roll information is certified annually in October.
The section below provides an overview of the calculation components used when a qualifying property event has occurred.
Market Value
One component in the property tax calculation is the market value (as defined by ORS 308.205) of the new construction or remodeling, etc., based on the annual January 1st assessment date.
If you are hiring a contractor to do the work, the cost of construction might be one type of an estimate for the value of the new construction or remodeling. However, keep in mind that the cost does not necessarily equal market value.
Changed Property Ratio (CPR)
Another component in the calculation is called the Changed Property Ratio (CPR) which is a requirement per Oregon Administrative Rule (OAR) 150-308-0170.
The CPR is determined each year by dividing all unchanged properties maximum assessed value by their real market value. The ratio is calculated for each property class, such as Residential, Commercial, or Industrial. Some cities have elected to have their CPR calculated with only the properties located in their respective city.
You may look up the most recently certified CPR information here: Changed Property Ratios
Please note: The CPR information provided in the link above is for prior tax years, and the ratios change each tax year. Any future property event’s calculation would be subject to that future year’s ratios.
Tax Rate
Another component in the calculation is the tax rate or millage rate. The millage rate includes current bonds and levies, and the rate can increase or decrease in future tax years by any amount, depending on what new bonds or levies are being voted in or if any are expiring. Tax rates vary by code area.
You may view the most recently certified tax rate information for a property via the options listed below. Rates are expressed in dollars per thousand dollars of taxable assessed value.
Property Value and Tax Graphs - Search by Property ID or address to view the 5-year tax rate history for the property and determine whether or not the property is in compression. Properties in compression may experience a different tax impact due to changes in the Real Market Value; questions around compression can be directed to propertytax@multco.us. It should also be noted that newly created properties would not have a tax graph associated with that account until the 1st certified year.
Levy Code Rate Sheet - View the “Total All Rates” column by “code area” to see the most recently certified tax rate information. (You may locate the "code area" on the tax bill or contact propertytax@multco.us for help with determining a property’s code area.)
Please note: The tax rate information provided via the options above is prior tax year information, and the tax rates change each year. Any future property event’s calculation would be subject to that future year’s tax rate.
Example Formulas
Warning: The examples shown below will not result in the actual property tax calculation for a future tax year, as using historical Changed Property Ratios and historical tax rates will probably be inaccurate as both will not be the same for a future tax year. Changed Property Ratios change every year, and additional bonds or other measures are often passed annually by the public which can affect the tax rate. Also, results for properties going into or out of compression in a future tax year may differ.
With that caution in mind, the formulas can be thought of as these examples below:
- ((New Real Market Value Added x Changed Property Ratio)/1000) x Millage Rate) = New Additional Tax
Or…
- Estimated Market Value of New Improvements x CPR = Additional Assessed Value
- (Additional Assessed Value/1000) x Tax Rate = Estimated Additional Tax Amount
Calculation Exercise Example
Warning: This example calculation below is only for the purpose of demonstrating the mechanics of the formula, and does not represent a specific value or tax change for any specific property, nor is the example below related to any particular property’s valuation or assessment.
In this example below, let’s use $100,000 as the “New Real Market Value Added”, and let’s use 0.481 as the example “Changed Property Ratio (CPR)”. We will use 26.9449 as the example tax rate/millage rate. Disclaimer: These numbers are for demonstration purposes only and not an accurate calculation of taxes for the current year.
$100,000 x .481 = $48,100 Additional Assessed Value
$48,100/1000 = 48.10
48.10 x 26.9449 = $1,296.05 Estimated Additional Tax Amount
Permitting Fees and Building Requirements
For information on permitting fees and building requirements, please contact the permitting jurisdiction for your property. The Multnomah County Assessor’s Office is not the authority for permitting or building requirements.