Oregon Measure 50 Property Tax Calculator

How this calculator works

Oregon's property-tax framework has been governed by Measure 50 (May 1997) and its predecessor Measure 5 (1990) for nearly thirty years. Codified at Article XI §§ 11 and 11b of the Oregon Constitution and implemented by ORS Chapter 308, the framework imposes three interlocking mechanics on every parcel in the state:

1. Maximum Assessed Value (MAV) frozen at 90% of 1995-96 Real Market Value (RMV). Article XI § 11(1)(a) set every existing parcel's base MAV at 90% of the 1995-96 assessment-roll RMV — a one-time constitutional reset.
2. 3% annual MAV cap. Article XI § 11(1)(b) limits year-over-year MAV growth to no more than 3% per year for an existing parcel.
3. Tax computed on the lesser of MAV or RMV. ORS 308.146(2) requires taxable value to be the lower of MAV and RMV.

Then a combined-rate cap of $15 per $1,000 of assessed value (Article XI § 11b, Measure 5) applies on top, with compression under ORS 310.150 proportionally reducing per-district levies when the cap is breached. Voter-approved general-obligation bond levies are outside the cap and add on top.

The math is clean once you have MAV, RMV, and the combined rate:

• this-year MAV = min(supplied current MAV, prior-year MAV × 1.03)
• taxable value = min(MAV, RMV)
• annual tax = taxable value × combined rate

Everything else in this calculator is the senior deferral eligibility check and the compression flag.

The 1997 MAV reset — 90% of 1995-96 RMV

Measure 50 was unusual in that it did not merely freeze tax bills forward — it REWROTE the base. On the 1997 transition, every existing Oregon parcel had its Maximum Assessed Value set, by constitutional fiat, at 90% of the parcel's 1995-96 Real Market Value. A property worth $200,000 on the 1995-96 assessment roll started Measure 50 with a base MAV of $180,000, regardless of what it was worth in May 1997 when voters ratified the measure. From that base, MAV has compounded at no more than 3% per year ever since.

The mechanic is fundamental: a Portland home assessed at $200,000 in 1995-96 has a 2026 MAV of approximately $180,000 × 1.03^29 ≈ $424,000. The current Real Market Value of the same home might be $850,000 or more — Portland appreciation since 1995-96 has averaged roughly 7-8% per year — but tax is computed on the lower MAV figure under the ORS 308.146(2) "lesser of" rule.

The 3% annual MAV cap

Article XI § 11(1)(b) caps year-over-year growth in Maximum Assessed Value at no more than 3% per year. The cap compounds: a 1997 base MAV of $180,000 grows to roughly $186,000 in 1998, $192,000 in 1999, and so forth — modest in any single year, substantial over decades.

The cap does NOT apply in three cases — the "Class B exception" mechanics under ORS 308.146(3):

• New construction — the year a new home is built, MAV is set to current RMV.
• Major improvements — additions, new garages, new pools, ADUs, gut renovations that change square footage or use trigger an MAV reset to post-improvement RMV.
• Partitions and lot-line adjustments — subdividing a lot or shifting boundaries triggers re-valuation of the resulting parcels.

After a Class B reset, the 3% annual cap starts fresh the following year from the new base. The reset is irreversible and is the principal reason many Oregon homeowners delay major remodels.

The "lesser of MAV or RMV" rule

ORS 308.146(2) implements the constitutional rule from Article XI § 11(1)(c): taxable value is the LOWER of Maximum Assessed Value (MAV) and Real Market Value (RMV). In a typical rising market where RMV grows faster than the 3% MAV cap, MAV is the lower figure and the property is taxed on MAV. In a market downturn where RMV drops below the cap-grown MAV, the property is temporarily taxed on the lower RMV (the "M5 value" in assessor parlance — a holdover label from the Measure 5 era).

The important nuance: when the market recovers, MAV resumes growing at 3% per year from its existing base. The temporary RMV-below-MAV adjustment does NOT reset MAV downward. A parcel that had MAV $400K and saw RMV drop to $350K in a downturn pays tax on $350K that year but, when RMV recovers above $400K, returns to paying tax on the cap-grown MAV — the temporary discount is exactly that, temporary.

The $15 per $1,000 statutory rate cap and compression

Article XI § 11b — added to the constitution by Measure 5 (1990) and retained by Measure 50 — caps the combined property tax rate at $15 per $1,000 of assessed value: $5/$1,000 for education (school operating) and $10/$1,000 for general government (county, city, special districts). When the sum of district levies on a parcel would exceed the cap, taxes are "compressed" under ORS 310.150 — each district's levy is proportionally reduced until the combined rate equals the cap.

Compression is common in Portland (Multnomah County), Eugene (Lane County), and Bend (Deschutes County), where high school-bond and operating-levy activity routinely push the combined rate above the statutory cap. A typical Portland bill consists of:

• The compressed $15/$1,000 operating taxes (school + general government)
• Plus uncompressed voter-approved general-obligation bond levies (outside the cap under § 11b(2))

Voter-approved bond levies are what push Portland's actual combined effective rates above 1.5% of MAV — the cap restricts only the operating portion.

A worked example — Portland home, owned through 1995-96 base year

A Portland home assessed at $200,000 in 1995-96. Owner has held the property continuously since before the base year. No Class B improvements have occurred. Current RMV is $850,000. Combined tax rate is $15/$1,000 (Multnomah County, at the statutory cap).

• 1997 base MAV: $200,000 × 0.90 = $180,000
• 2026 MAV (after 29 years of 3% compound): $180,000 × 1.03^29 ≈ $424,000
• Current RMV: $850,000
• Taxable value (lesser of MAV or RMV): $424,000 (MAV is lower)
• Tax owed: $424,000 × 0.0150 = $6,360
• Effective rate on RMV: $6,360 / $850,000 = 0.75%

A new buyer purchasing this same property at $850,000 in 2026 would inherit the locked-in MAV of $424,000 — Oregon's MAV is property-tied, not owner-tied (the key structural difference from California Prop 13). The next buyer pays $6,360, not the $12,750 that an uncapped $850,000 RMV at 1.5% would produce. The 60% structural savings transfers with the deed.

A worked example — same home with a major addition

Same Portland home, owner adds a $200,000 second-story addition in 2024. The addition triggers a Class B reset under ORS 308.146(3) — MAV resets to current post-improvement RMV in 2024.

• 2024 post-improvement RMV: $850,000 (assume value-add equal to construction cost)
• 2024 MAV (Class B reset): $850,000 (reset to RMV in the year of the improvement)
• 2026 MAV (after two years of 3% growth): $850,000 × 1.03^2 ≈ $901,775
• 2026 RMV: $900,000
• Taxable value (lesser of MAV or RMV): $900,000 (RMV is now lower)
• Tax owed: $900,000 × 0.0150 = $13,500

The owner who held continuously and didn't add the addition pays $6,360 — the owner who did the same hold but added the addition pays $13,500. The reset is irreversible, and the lost MAV protection compounds forward forever. This is the structural reason long-tenured Oregon homeowners often delay or scale down major remodels until the property is sold.

A worked example — Bend home with the MAV cap binding

A $500,000 Bend home in Deschutes County. The owner bought ten years ago at $350,000, which became the post-2016 MAV. Cap has bound every year since. Combined Deschutes rate is $12.50/$1,000 (below the statutory cap; no compression).

• 2026 MAV (after 10 years of 3% compound from $350K): $350,000 × 1.03^10 ≈ $470,500
• Cap ceiling: prior MAV × 1.03 = $456,800 × 1.03 ≈ $470,500
• Current RMV: $500,000
• Taxable value (lesser of MAV or RMV): $470,500 (MAV is lower)
• Tax owed: $470,500 × 0.01250 = $5,881
• Tax on uncapped RMV: $500,000 × 0.01250 = $6,250
• Annual savings from MAV cap: $369

The cap savings are modest in any single year ($369) but compound over time — after a decade of holding, the cumulative savings vs an uncapped baseline are in the thousands. As the gap between MAV and RMV widens, annual savings grow.

A worked example — senior deferral, age 67, $40K income

Same Bend home, owner is now 67 years old with $40,000 of household income (well under the $60,000 limit for the 2026 program year). The owner has occupied the home for ten years (exceeds the five-year minimum) and reports net worth excluding the home of $200,000 (under the $500,000 limit).

• Annual tax computed above: $5,881
• ORS 311.668 deferral: the owner can defer payment of the entire $5,881
• Interest accrual: 6% simple interest per year on deferred balances under ORS 311.674
• Lien: a statutory lien under ORS 311.673 attaches to the property and is due at sale, change of residence, or death of the last qualifying owner

After five years of deferring at $5,881/year with 6% simple interest, the lien balance accumulates to approximately $32,000–$34,000 (depending on the timing of payments and interest accrual). The owner has preserved $5,881/year of cash flow at a substantially lower cost than a HELOC (typically 8%+ compound) or reverse mortgage. The trade-off: the lien reduces the equity transfer to heirs.

A worked example — same owner makes a Class B improvement

Same Bend owner, adds a new $80,000 detached ADU in 2026. The ADU is a Class B improvement and triggers an MAV reset for the post-improvement parcel.

• Pre-improvement MAV: $470,500
• ADU value-add: $80,000 (assume value-add equal to construction cost)
• 2026 post-improvement RMV: $580,000 ($500,000 + $80,000)
• 2026 MAV (Class B reset): $580,000
• Tax owed at $12.50/$1,000: $580,000 × 0.01250 = $7,250
• Pre-improvement tax: $5,881
• Annual tax increase from the ADU: $1,369 (in addition to the construction cost)

The $1,369 annual increase is permanent — it compounds at 3% going forward from the new $580,000 MAV base. Over a 20-year hold post-ADU, the cumulative additional tax exceeds $30,000 in undiscounted dollars. Many Oregon homeowners considering ADUs run this calculation explicitly: the rental income from the ADU must exceed the construction cost amortization PLUS the permanent tax increase.

How Oregon compares to other state caps

| State | Annual cap | Applies to | Reset on sale? | Notes | | --- | --- | --- | --- | --- | | California (Prop 13) | 2% assessed value | All real property | YES — full reassessment | Most aggressive cap; resets on every change of ownership | | Oregon (Measure 50) | 3% MAV | All real property | NO — property-tied | MAV stays with the property across owners | | Florida (Save Our Homes) | 3% assessed value | Homestead only | Partial (with portability) | Owner-tied; portability when owner moves | | Arizona (Prop 117) | 5% LPV | All real property | NO — property-tied | Two-tier FCV/LPV structure | | Texas (§ 23.23) | 10% appraised value | Homestead only | YES — full reset at sale | Owner-tied; § 11.13 exemption stack | | Most Midwest / Northeast | none | n/a | n/a | Assessed value tracks market |

Oregon's 3% sits in the middle band, but the property-tied (not owner-tied) nature of the cap is unusual. California's 2% cap is more protective per year, but every California sale resets the basis to market — long-tenured single-owner families benefit, but the protection does not transfer to a buyer. Oregon's MAV transfers with the deed, producing a different equilibrium: properties accumulate MAV protection over decades regardless of ownership turnover.

Combined tax rate variation by Oregon county

| County | Population center | Typical combined rate (per $1,000) | Notes | | --- | --- | --- | --- | | Multnomah | Portland | ~$15.00 | At the statutory cap; compression common | | Washington | Beaverton / Hillsboro | ~$14.20 | High operating levies; partial compression | | Lane | Eugene / Springfield | ~$14.00 | High school-bond activity | | Marion | Salem | ~$14.50 | State-capital district overhead | | Clackamas | Oregon City / Lake Oswego | ~$13.50 | Lower than Multnomah | | Benton | Corvallis | ~$14.00 | University-area levies | | Linn | Albany / Lebanon | ~$14.00 | Mid-Willamette Valley | | Jackson | Medford / Ashland | ~$13.50 | Southern Oregon | | Deschutes | Bend / Redmond | ~$12.50 | Lower than Willamette Valley | | Douglas | Roseburg | ~$12.50 | Southern Oregon, lower bond activity |

Pull the binding combined rate for the specific parcel from the county tax certification — Oregon county treasurers publish per-parcel breakdowns showing each district's contribution.

Common errors to avoid

• Computing tax on RMV instead of MAV. A common out-of-state-buyer error. The Notice of Value prints both numbers; the taxable value is the LESSER of the two (ORS 308.146(2)). A long-tenured parcel can be off by 40-60% if RMV is used by mistake.
• Assuming Oregon resets on sale like California. Oregon does NOT. MAV is property-tied — a new buyer inherits the seller's locked-in MAV. The tax savings from the 3% compound cap transfer with the deed.
• Underestimating Class B improvement resets. Pulling permits for an addition, ADU, or substantial remodel triggers an MAV reset under ORS 308.146(3). The next year's MAV jumps to post-improvement RMV and the 3% cap starts fresh from there. Run the tax calculation BEFORE pulling permits.
• Forgetting that compression is real in Portland, Eugene, and Bend. When the nominal combined rate exceeds $15/$1,000, ORS 310.150 compression proportionally reduces per-district levies. The actual collected tax can be 5-15% below the nominal computation. Use the post-compression figure from the county tax certification for planning.
• Treating voter-approved bonds as inside the cap. Voter-approved general-obligation bond levies are OUTSIDE the $15/$1,000 cap under Article XI § 11b(2). Portland's actual effective rates exceed 1.5% of MAV because of layered bond levies, not because the operating cap is breached.
• Missing the senior deferral five-year residency requirement. ORS 311.668 requires five years of continuous occupancy as primary residence — recent relocations to Oregon disqualify even when the owner is otherwise 62+ and within the income limit.

Tools, not advice. Confirm MAV, RMV, and the combined tax rate from the county assessor's Notice of Value and the county tax certification before relying on any result for planning purposes.