Clackamas county tax assessor: what every homeowner needs to know

Last updated 2026-07-09

What does the Clackamas County Assessor actually do?

The Clackamas County Assessor values every parcel in the county as of the January 1 assessment date, keeps ownership records, and runs the exemption and deferral programs. ^[1] It does not set your tax rate. That job belongs to the county's taxing districts, which add up their levies and apply them to your assessed value.

Oregon carries two values on every property at once. Real Market Value (RMV) is the assessor's estimate of what your home would sell for in an arm's-length deal. Maximum Assessed Value (MAV) is the number your tax actually rides on, and for anyone who has owned a while, it sits well below RMV. ^[2]

The office is at 150 Beavercreek Road in Oregon City. The main tax line is (503) 655-8671. Hours have long run Monday through Friday, 8:00 a.m. to 5:00 p.m., but call first or check the website before you drive out. Hours move around holidays and budget cycles.

How does Oregon's 3% cap protect Clackamas County homeowners?

Oregon Measure 50 (1997) rewrote how property tax works statewide. It created the MAV system and locked in a hard rule: MAV can grow no more than 3% a year, no matter how fast the market runs. ^[2] The Oregon Department of Revenue's Property Tax Division enforces it across every county.

Here is how that lands in practice. Say your RMV jumps 12% in a hot year. Your MAV still rises only 3%. Your tax follows the MAV, not the RMV, so the bill crawls up while the market sprints. Year after year, the gap between the two widens. Long-term owners end up taxed on a fraction of what their home is worth.

There is one big exception. Add real new construction and the assessor bolts the new value onto your MAV outside the 3% cap. A major addition, a new garage, or an ADU each trigger a separate MAV calculation for that improvement. ^[3] So if your bill spiked right after you pulled a remodel permit, that is almost certainly why.

The table below shows the cap at work over five years. It assumes 10% annual market appreciation on a home that starts at $400,000 RMV and $320,000 MAV.

Year	RMV (10%/yr growth)	MAV (3%/yr cap)	Tax Savings vs. RMV (at 1.2% rate)
1	$400,000	$320,000	$960
2	$440,000	$329,600	$1,326
3	$484,000	$339,488	$1,738
4	$532,400	$349,673	$2,193
5	$585,640	$360,163	$2,706

That is real money, and it compounds. It is also why the neighbor who bought last year can owe far more than you do on a nearly identical house.

How does Clackamas County calculate your property's real market value?

The assessor runs three standard appraisal approaches and weights them by property type. ^[4]

Sales comparison rules for houses. The assessor pulls recent arm's-length sales of comparable homes (comps) in your neighborhood, then adjusts for size, age, condition, lot size, and features. A private appraiser does the exact same thing. So will you, if you appeal.

The cost approach estimates what it would take to rebuild the structure new, then subtracts depreciation. It shows up more for newer homes and oddball properties where comps are thin.

The income approach covers rentals and commercial buildings. The assessor capitalizes net operating income at a market cap rate to reach a value. Own rentals in Clackamas County? Your actual rents and vacancy rates feed the number.

The assessor reappraises the county on a rolling cycle, not every parcel every year. Mass appraisal models value large groups of similar homes at once. That saves money and it breeds error. A model built on homes that sold along a main road can badly misjudge your cul-de-sac lot. That error is exactly what an appeal fixes.

When is the deadline to appeal a Clackamas County property tax assessment?

Oregon runs one statewide appeal deadline. Petitions to the Board of Property Tax Appeals (BOPTA) must be filed by December 31 of the tax year. ^[5] For the 2025-26 tax year, that is December 31, 2025.

Don't confuse that with your payment due dates. Oregon property taxes get billed in November and can be paid in three installments: November 15, February 15, and May 15. Miss a payment date and you owe interest. Miss the BOPTA petition deadline and your appeal dies for the year. There is no grace period.

The petition (Form OR-BOPTA) goes to the county clerk, not the assessor. ^[5] In Clackamas County that is the County Clerk at 150 Beavercreek Road, Oregon City. A filing fee applies. In recent years it has run $25 for the first three tax accounts on one petition and $5 for each account after that. Fees are set by county ordinance and can change, so confirm the current number when you file.

Lose at BOPTA and you can push on to the Oregon Tax Court Magistrate Division within 30 days of BOPTA's written decision. The filing fee there is $310 (as of 2024, set by Oregon law). ^[6] Most homeowners stop at BOPTA. The Tax Court step earns its keep only when the dollars in dispute are large.

What evidence wins a Clackamas County property tax appeal?

BOPTA is a local board, usually three county commissioners or their appointees. They are not appraisers, but they know real estate. They want data, not a rant.

Recent comparable sales are your strongest card. Pull sales of homes like yours that closed in the 12 months before January 1 of the tax year. Clackamas County assessment records are searchable through the county's property portal ^[1], and Oregon's statutes live on the legislature's site, but for actual sale prices, lean on the county assessor's search, Redfin or Zillow sold listings, or a real estate agent's CMA (comparative market analysis).

For each comp, write down the address, sale date, sale price, square footage, lot size, age, and condition. If your home has defects that drag down its market value, photograph them and get written repair estimates. A leaking roof, a foundation crack, a dying HVAC system: each one supports a lower RMV. Board members respond to repair bids.

One trap. If your RMV already sits below your MAV, appealing RMV alone buys you nothing, because your tax rides on MAV. In that case (it happens after a downturn) you appeal to have the county recognize an exception to MAV, which can lock the lower RMV in as your new MAV going forward. ^[2]

Want a system for organizing comps, running comparable adjustments, and filling out the BOPTA petition? TaxFightBack's DIY appeal kit walks you through each step, with no contingency firm skimming your savings.

Oregon's process is friendlier to do-it-yourselfers than what you hit in a state like Texas. If you have ever stared at how the bexar county tax assessor or the gwinnett county tax assessor systems run, you will find Oregon's single December 31 deadline and one plain petition form a relief.

What exemptions can reduce a Clackamas County property tax bill?

Oregon has several exemption and deferral programs, all run at the county level. These matter most to Clackamas County homeowners:

Disabled and Senior Citizen Deferral. Oregon's deferral program lets qualifying seniors (age 62 or older) and people with disabilities defer property taxes until the home sells or the owner dies. The state pays the tax and records a lien. To qualify, household income must be $47,000 or less (as of 2024, adjusted each year). ^[7] Apply to the Oregon Department of Revenue by April 15.

Veteran's Exemption. Oregon takes $27,390 off RMV (the amount adjusts each year with the Portland-area CPI) for qualifying veterans or their surviving spouses. You need a service-connected disability rating, though a surviving spouse of a wartime veteran may qualify in some cases regardless of rating. ^[8] File with the Clackamas County Assessor by April 1 of the tax year you want it applied.

Seismic Retrofit Exemption. Oregon exempts the value added by certain seismic retrofits for 10 years under ORS 307.175. ^[3]

Farm and Forest Deferral. Farmland and forest land assessed under special-use rules carry much lower assessed values. If you own acreage, look into this on its own.

Miss a deadline and you lose a full year of the benefit. The April 1 veteran's deadline and the April 15 deferral deadline are firm. Mark them.

How do I find my Clackamas County property tax records online?

The county runs an online property search tool at the Clackamas County Assessor website (clackamas.us/at). ^[1] Search by address, map tax lot number, or owner name. The record shows your current RMV, MAV, and assessed value (AV), plus the breakdown of taxing-district levies that build your total bill.

Your property tax statement arrives by mail in October. It carries your account number, which you need on the BOPTA petition. Lost the statement? The portal lets you reprint it.

The county's Geographic Information System (GIS) mapping tool (maps.clackamas.us) shows parcel boundaries and helps you spot neighboring lots for comp research. Grab the map and tax lot number of a comparable home, pull its assessment record, and see what the county values it at. That is a quick sanity check before you file.

If you know other big-county systems, the Clackamas portal works much like tools used by los angeles county property tax or san diego property tax. Oregon's dual-value setup (RMV and MAV) just makes the output harder to read at first.

What is the Clackamas County Board of Property Tax Appeals and how does it work?

BOPTA is a local quasi-judicial panel, usually county commissioners or appointed citizens, that hears residential and commercial appeals. It is separate from the assessor's office. ^[5]

File your petition by December 31 and the clerk schedules a hearing, typically between January and April. You get written notice of the date and time.

At the hearing you present your evidence. The assessor's office sends someone to defend the current value. You speak, they respond, the board asks questions. Twenty to 45 minutes, usually. No lawyer needed. Dress neatly. Bring three copies of every document: one for the board, one for the assessor's rep, one for you.

BOPTA can cut your RMV, leave it alone, or in rare cases raise it. Oregon law bars the board from lifting your value above what the assessor originally set unless the assessor formally asks for an increase. ^[5] That keeps a hearing from backfiring on you.

Decisions come in writing, usually within a few weeks. Win, and the lower value applies to the tax year under appeal. Any overpayment gets refunded or, more often, credited to your next bill.

How do Clackamas County property taxes compare to neighboring counties in Oregon?

Oregon's MAV cap means the mechanism is identical statewide, but effective rates differ because each county carries its own mix of taxing districts and levy rates. ^[2]

Clackamas County's effective rate has long run around 1.0% to 1.2% of RMV, depending on the district you sit in. Cities like Lake Oswego and Milwaukie stack their own levies on top of county and school levies. Multnomah County, which holds Portland proper, tends to run a bit higher on more urban districts. Washington County has generally tracked close to Clackamas.

The Oregon Department of Revenue publishes a Statistics of Assessed Value report every year that breaks out MAV and RMV totals county by county. ^[7] It is the cleanest place to compare how much compression (the gap between RMV and MAV) each county has built up.

Set against the rest of the country, these rates look small. Systems like maricopa property tax in Arizona and lake county property tax in Illinois can hit 1.5% to 3.5% of market value, which is why Oregon's MAV protection means so much to long-term owners.

What if my Clackamas County property was recently purchased at a price lower than its assessed value?

This one trips people up. In Oregon, a sale does not reset your MAV. When you buy, the assessor looks at the deal but does not swap your MAV to match your purchase price. ^[2]

But if you paid less than the current RMV, that sale is strong evidence the RMV is too high. Petition BOPTA and argue the RMV should drop to your purchase price or near it. If the board agrees and the new RMV falls below your current MAV, the MAV has to drop with it, because MAV cannot exceed RMV under the law.

A fresh purchase price is about the best market evidence there is, which makes this one of the most winnable appeals you can file. Your purchase agreement and closing statement are your lead exhibits. Bring both to the hearing.

New construction plays by different rules. A brand-new home gets its first MAV set at 100% of its specially assessed value in the opening assessment year, off the cost approach. After that, the 3% annual cap kicks in going forward. ^[3]

How do I contact the Clackamas County Assessor's office and what can they help with?

The Clackamas County Assessment and Taxation office is at 150 Beavercreek Road, Oregon City, OR 97045. ^[1] Phone: (503) 655-8671. Website: clackamas.us/at.

Staff can walk you through your value notice, explain the district-by-district breakdown of your bill, answer exemption-eligibility questions, and hand you petition forms. They will not argue for a lower value (not their job), but ask politely and most will explain how they reached a number.

Want an informal review before you file? Call and ask whether the office offers a pre-petition meeting. Some Oregon counties do, some don't. An informal review does not waive your right to file a formal BOPTA petition, and it sometimes clears up an obvious error without a hearing at all.

The structure here mirrors offices elsewhere. The madison county tax assessor in Alabama and the cherokee county tax assessor in Georgia also run informal reviews before formal appeals. Calling first pays off.

If your problem is a clerical error (wrong square footage, wrong property class, a building torn down but still on the rolls), call the assessor directly. Those get fixed administratively, no hearing. The formal appeal process is for real valuation fights.

Before you call, pull your record online and jot down your account number, current RMV, MAV, and assessed value. It saves time and tells the staff you have done the work. TaxFightBack's appeal kit includes a one-page pre-call checklist if you want a prompt.

Frequently asked questions

What is the deadline to appeal my Clackamas County property tax assessment?

The deadline to file a petition with the Clackamas County Board of Property Tax Appeals (BOPTA) is December 31 of the tax year you are appealing. For the 2025-26 tax year, that is December 31, 2025. File with the County Clerk, not the assessor's office, and pay the $25 filing fee (confirm the current amount before filing, since fees change by county ordinance).

What is the difference between RMV and MAV on my Clackamas County tax statement?

RMV is Real Market Value, the assessor's estimate of what your home would sell for today. MAV is Maximum Assessed Value, the number your tax is actually calculated on. Oregon's Measure 50 caps MAV growth at 3% per year regardless of the market. For most long-term owners, MAV sits well below RMV, which is the whole point of the cap.

Can the Board of Property Tax Appeals raise my assessed value after I file an appeal?

BOPTA cannot raise your value above what the assessor originally set unless the assessor formally requests an increase at the hearing. In practice, boards almost never raise values in a homeowner-initiated appeal. Oregon's BOPTA rules protect you from an appeal backfiring just because you showed up and asked questions.

Does buying my home at a price lower than assessed value automatically lower my taxes?

No. In Oregon, a sale does not reset your MAV. But your purchase price is strong evidence of RMV, and you can use it in a BOPTA appeal. If the board accepts your purchase price as the RMV and that new RMV falls below the current MAV, the MAV must drop to match it. Bring your purchase agreement and closing statement to the hearing.

What exemptions are available through the Clackamas County Assessor?

Key programs include Oregon's Senior and Disabled Citizen Property Tax Deferral (income limit $47,000 as of 2024, apply by April 15), the Veteran's Exemption of roughly $27,390 off RMV for qualifying disabled veterans (apply by April 1), and a seismic retrofit exemption for certain home improvements. Farm and forest land also qualify for special assessed values under separate programs.

How do I look up my Clackamas County property records online?

Go to clackamas.us/at and use the property search tool. Search by address, owner name, or map tax lot number. The record shows your current RMV, MAV, assessed value, and the levies that make up your total bill. Your account number from this record is required on the BOPTA petition form.

What happens at a Clackamas County BOPTA hearing?

The hearing runs 20 to 45 minutes. You present your evidence (comparable sales, photos, repair estimates). The assessor's representative defends the current value. The board asks questions and deliberates. Bring three copies of all documents. No lawyer is required. The board mails a written decision within a few weeks. A win results in a refund or credit of any overpaid tax.

How does Oregon's 3% annual cap affect my Clackamas County property tax?

Under Oregon Measure 50, your MAV can grow by no more than 3% per year even if RMV climbs 10% or 15%. Your tax is calculated on MAV. Over time, this creates a growing gap between what your home is worth and what you are taxed on. New construction and major improvements added under permit can trigger extra MAV increases outside the cap.

What evidence is most effective in a Clackamas County property tax appeal?

Recent comparable sales of similar homes that closed in the 12 months before January 1 of the tax year are the strongest evidence. For each comp, document address, sale date, sale price, square footage, age, and condition. Photographs of property defects and written repair estimates from licensed contractors also carry real weight with the board.

Do I need a lawyer or a property tax consultant to appeal my Clackamas County taxes?

No. Oregon's BOPTA process is built for self-represented homeowners. You file a form, pay $25, and present evidence at a short hearing. Contingency firms typically charge 25% to 40% of your first-year savings. On $400 of annual savings, that is $100 to $160 handed away for work you can do yourself in a few hours.

When do Clackamas County property tax bills go out and when are they due?

Tax statements mail in October. The first-installment due date is November 15. You can also pay in two later installments: February 15 and May 15 of the following year. Pay the full amount by November 15 and you get a 3% discount. Missing an installment date triggers interest on the overdue amount.

What is the phone number and address for the Clackamas County Assessor?

The Clackamas County Assessment and Taxation office is at 150 Beavercreek Road, Oregon City, OR 97045. Phone: (503) 655-8671. Office hours are generally Monday through Friday, 8:00 a.m. to 5:00 p.m. Check clackamas.us/at for any changes before visiting in person.

What is the effective property tax rate in Clackamas County?

Clackamas County effective rates have historically ranged from about 1.0% to 1.2% of RMV, varying by taxing district (cities like Lake Oswego carry extra levies). Because Oregon taxes on MAV rather than RMV, long-term owners often pay an effective rate well below 1% of current market value. The Oregon Department of Revenue's annual statistics report has county-by-county data.

Can I appeal my Clackamas County taxes if I think the square footage or property details are wrong?

Yes, but call the assessor's office first for a clerical correction. If the record shows the wrong square footage, wrong bedroom count, or a demolished structure, those often get fixed administratively without a formal appeal. Bring documentation: a floor plan, permit records, or a prior appraisal that shows the correct data. Formal BOPTA appeals are for valuation disputes.

Sources

1. Clackamas County Assessment and Taxation, Property Search Portal: Clackamas County Assessor office location (150 Beavercreek Road, Oregon City), phone (503) 655-8671, and online property search tool
2. Oregon Department of Revenue, Property Tax Division: Understanding Your Property Taxes: Oregon Measure 50 created the MAV system, caps MAV growth at 3% per year, and MAV cannot exceed RMV
3. Oregon Revised Statutes ORS Chapter 308, Assessment of Property for Taxation: New construction triggers additional MAV calculation outside the 3% cap; seismic retrofit exemption under ORS 307.175
4. Oregon Department of Revenue, Property Tax Programs: Oregon assessors use sales comparison, cost, and income approaches in mass appraisal models
5. Oregon Revised Statutes ORS Chapter 309, Board of Property Tax Appeals: BOPTA petition deadline is December 31 of the tax year; BOPTA cannot raise value above assessor's original figure unless assessor requests it; petitions filed with county clerk
6. Oregon Tax Court, Magistrate Division Filing Information: Oregon Tax Court Magistrate Division filing fee is $310; appeals from BOPTA must be filed within 30 days of BOPTA written decision
7. Oregon Department of Revenue, Senior and Disabled Citizen Property Tax Deferral Program: Deferral income limit is $47,000 for 2024; qualifying age 62 or older; application deadline April 15 each year; annual Statistics of Assessed Value report by county
8. Oregon Department of Revenue, Property Tax Exemptions: Oregon veteran's property tax exemption is approximately $27,390 off RMV (adjusted annually by Portland area CPI); application deadline April 1 with county assessor
9. Oregon Revised Statutes ORS Chapter 307, Property Subject to Taxation: Qualifying seismic retrofit improvements are exempt from property tax for 10 years under ORS 307.175