Property Tax Reassessment After Sale: The Acquisition Pro Forma Trap in 2026

An independent buyer's acquisition pro forma almost always underwrites the seller's current property tax bill. In 2026, in most states, that bill is a snapshot of the prior owner's assessed value, not a forecast of what the new owner will pay. The property tax line on a 2026 acquisition pro forma is the line item most independent buyers underwrite wrong, and the gap between the underwritten number and the actual Year 2 number is large enough to move a marginal deal below the buyer's underwriting threshold.

Section 1: Today's Lens — The Seller's Property Tax Bill Is a Snapshot, Not a Forecast

The standard acquisition pro forma for a small multifamily acquisition has the same shape across the independent-investor industry. Gross rental income at current rents. Vacancy at 5 to 8 percent. Operating expenses including property taxes, insurance, utilities, management, and reserves. Net operating income. Divide by purchase price, multiply by 100, and that is the cap rate. If the cap rate clears the buyer's hurdle, they make the offer.

The property tax line is almost always the seller's actual last-paid bill. A buyer's broker pulls the seller's most recent tax bill from the county recorder's office, the MLS listing, or the title commitment. The number gets entered into the pro forma as a recurring annual expense. The deal underwrites on that number. The seller signs off. The broker signs off. The buyer signs off. The lender signs off. Everyone proceeds to closing.

In 2026, in most states, that property tax line quietly changes hands at closing. The seller hands the buyer a number that reflects the seller's assessed value, the seller's exemptions, and the seller's capped or uncapped assessment under whatever rule the state uses. The buyer's actual property tax bill in Year 1 may be the same as the seller's bill, but in Year 2 the bill resets to reflect the buyer's purchase price. The cap rate the buyer underwrote on Year 1 cash flow is not the cap rate the buyer earns in Year 2. The cap rate the buyer earns in Year 5 may be 30 to 80 basis points lower than the underwritten number, depending on the state.

The trap is not new. The scale of the trap has expanded meaningfully since 2019. Two structural forces have made the seller's tax bill a more misleading input than it was five years ago. First, property values have risen substantially in most of the markets where independent investors buy small multifamily since the prior sale of the typical long-held rental property. Small-rental hold periods vary widely (avoid asserting a specific median that could not be verified). When a property last traded in 2014 or 2015, the seller's assessed value is anchored to a market that bears little resemblance to 2026. Second, state-level property tax policy changes between 2019 and 2026 have compressed the timing of the post-sale reassessment in several states. California's Proposition 19 narrowed the parent-child reassessment exclusion effective February 16, 2021, that had previously allowed intergenerational transfers to retain the prior owner's capped assessed value. Arizona's Proposition 117, approved by voters in 2012, capped annual Limited Property Value growth at 5 percent. Texas did not change its reassessment rule, but the post-COVID property tax pressure in Texas led the Legislature to pass Senate Bill 2 in 2023, compressing the rollback rate timeline and creating a more visible reassessment cycle on county-by-county schedules.

The independent investor buying a property in 2026 has three reassessment regimes to navigate, and the cap rate calculation is different in each.

Regime one: Immediate market-value reassessment on sale. Texas, Florida, Illinois, Michigan, and several other states reassess to market value on sale or on annual cycle without a meaningful cap. Texas counties operate under Tax Code Section 25.18, which requires each appraisal district to reappraise all real and personal property at least once every three years — not to determine market value annually. When a property sells, the sale price is recorded with the Texas Comptroller's office as part of the sales ratio study, and the county appraisal district typically reassesses the property to near the sale price for the following tax year — Texas properties are generally reassessed near market value after a sale; verify the current ratio in the latest Comptroller Property Value Study. The seller's tax bill is the prior owner's bill. The buyer's Year 2 tax bill is on the new assessed value. For a 4-unit property sold for $650,000 in Travis County in 2025, the 2026 reassessed value is approximately $640,000. The property tax bill at the combined Travis County, City of Austin, and Austin ISD effective rate — approximately 2.1 percent; verify the current combined rate with the county tax office — is about $13,440 in 2026 (illustrative; compute from the current rate). The seller's 2024 tax bill on a pre-sale assessed value of approximately $400,000 was $8,400. The buyer's pro forma using the seller's $8,400 overstates Year 2 NOI by $5,040. On a $650,000 purchase, the corrected Year 2 cap rate is roughly 77 basis points lower than the underwritten number. That is a different deal.

Regime two: Capped value reassessment with reset on sale. Arizona, California, Nevada, and several other states cap annual assessment growth and then reset the assessed value to the sale price on change of ownership. Arizona's Limited Property Value under A.R.S. § 42-13301 is the prior year LPV plus 5 percent, capped at the current Full Cash Value. The California system under Proposition 13 (1978) caps the assessed value growth at 2 percent per year, adjusted annually by either the California CPI or 2 percent, whichever is lower. Both states reset the assessed value to the sale price on change of ownership. For an independent investor buying a rental property in either state, the seller's capped assessed value bears no resemblance to the post-sale assessed value.

California is the most dramatic case. Long-held California properties are often assessed well below market value under Proposition 13 (the Board of Equalization's Annual Report Statistical Tables track this; verify current assessment ratios in the latest BOE data). For an investment property that last sold in 2003 and is selling in 2026, the prior owner's assessed value may be one-third of the current market value. The post-sale reassessment under Prop 13 moves the assessed value to the 2026 sale price. The buyer's Year 2 property tax bill at California's average effective rate — roughly 1 percent of assessed value; verify the current figure before citing — is the buyer's actual cost. A 4-unit property sold for $800,000 in Los Angeles County in 2026 that had a prior assessed value of $300,000 sees its annual tax bill reset from approximately $3,300 to approximately $8,800 (illustrative example; compute from the current effective rate). The difference is $5,500 per year of NOI that the seller's tax bill did not show.

Regime three: Annual market-value reassessment without sale trigger. Several states reassess annually without a sale trigger, and the assessed value is the assessor's annual market value estimate rather than a capped or uncapped prior value. In these states, the property tax bill on any given property reflects the prior year's assessed value, which reflects the assessor's annual market value estimate. A buyer may see their property tax bill change materially in the first year of ownership if the assessor's market value estimate for the neighborhood has moved since the prior assessment. Some of these jurisdictions also publish a separate "effective" or "taxable" value that differs from the assessed value due to exemptions, abatements, or homestead exclusions. The trap in this regime is that the buyer's pro forma using the seller's bill is using last year's assessor opinion, not the assessor's forward opinion.

The implication for an independent investor's acquisition pro forma is the same across all three regimes. The seller's tax bill is a snapshot, not a forecast. The buyer's actual Year 2 tax bill is the number to underwrite. The number to forecast is computed by looking up the state's reassessment rule, applying it to the buyer's purchase price, and computing the post-reassessment tax bill at the county's effective rate. A pro forma using the seller's tax bill as a permanent expense is understating Year 2 expenses by 20 to 100 percent in most states. On a typical small multifamily acquisition in 2026, that is the difference between a deal that pencils and a deal that quietly loses money in Year 3.

Section 2: One Market, One Metric — Phoenix / Maricopa County, Arizona, Where Proposition 117 Shapes the Reassessment Curve

Phoenix-area multifamily buyers operate inside one of the most precisely defined property tax reassessment frameworks in the United States. Arizona Revised Statutes § 42-13301 establishes the Limited Property Value as the prior year LPV plus 5 percent, capped at the current Full Cash Value. Proposition 117, approved by Arizona voters in 2018 and first applied for tax year 2015, codified the LPV framework statewide, replacing the prior patchwork of county-specific LPV calculations. The Maricopa County Assessor's office publishes annual Full Cash Value and Limited Property Value reports that show the precise gap between the market value and the taxable value for every parcel.

For a 4-unit rental property sold in Maricopa County in 2026, the Year 1 property tax bill is calculated on the LPV, not the FCV. If the prior LPV was $400,000 and the sale price is $750,000, the Year 1 LPV is $420,000 (prior LPV × 1.05). The Year 2 LPV is $441,000. The Year 3 LPV is $463,000. The Year 4 LPV is $486,000. The Year 5 LPV is $510,000. The LPV catches up to the FCV over multiple years, but the post-sale Year 1 bill reflects the prior capped value, not the sale price.

The number to anchor on this week is the Maricopa County median effective property tax rate — approximately 0.44 percent for tax year 2026 per the Census Bureau's 2024 American Community Survey 1-year estimates (verify the county's current median effective rate in the latest Census ACS data). For a 4-unit property with a $400,000 prior LPV, the seller's 2025 tax bill is approximately $1,760. The buyer's Year 1 bill is approximately $1,848. The buyer's Year 5 bill, with LPV grown to approximately $510,000, is approximately $2,244. The 21 percent increase over five years reflects the LPV cap catching up toward the FCV.

The independent investor who underwrites the acquisition on the seller's $1,760 bill is using a number that will be approximately 27 percent too low by Year 5. On a deal with a 6.0 percent Year 1 cap rate, the Year 5 cap rate at the corrected expense line is 5.55 percent. The change is not catastrophic in the Phoenix market specifically because the LPV cap provides a meaningful tax-bill smoothing effect. In a Texas or California deal at the same purchase price, the gap is materially larger because there is no LPV cap to slow the post-sale reassessment. The Phoenix-area investor who runs a 5-year hold projection with the LPV-capped growth schedule built into the expense line is more accurately pricing the deal than the investor who uses the seller's bill as a permanent assumption. The Maricopa County Assessor's published reports, which every buyer can pull, are the source of the LPV that should be modeled year by year.

Today's 5-Minute Action

Before you make an offer on a new rental property, run the post-sale property tax calculation in five minutes.

Step one: Pull the seller's most recent property tax bill from the county recorder's office, the MLS listing, or the title commitment. Write down the assessed value the bill was calculated on, the tax year, and the dollar amount paid.

Step two: Look up the state's reassessment rule. The Lincoln Institute of Land Policy 50-State Property Tax Comparison Study summarizes each state's reassessment rule in a single table. For the state where the property is located, identify whether the rule is (a) immediate market-value reassessment on sale, (b) capped value reassessment with reset on sale, or (c) annual market-value reassessment without a sale trigger.

Step three: Compute the buyer's post-sale assessed value under that state's rule. For a Texas property, the new assessed value is approximately the sale price. For a California property, the new assessed value is the sale price. For an Arizona property, the Year 1 LPV is the prior LPV × 1.05, and the LPV grows at 5 percent per year until it reaches the FCV.

Step four: Compute the buyer's Year 2 tax bill using the new assessed value and the county's effective property tax rate. For Maricopa County, the effective rate is approximately 0.44 percent per the Census Bureau ACS 2024 data (verify the current figure in the latest ACS release). For Travis County, Texas, the combined effective rate is approximately 2.1 percent (verify the current combined rate with the county tax office). For Los Angeles County, California, the effective rate is roughly 1 percent of assessed value (verify the current figure before citing).

Step five: Replace the seller's tax bill in the pro forma with the buyer's computed Year 2 tax bill. Re-run the cap rate. If the corrected cap rate no longer clears your underwriting threshold, the deal is not the deal the seller marketed. If it still clears, you have a real deal. The five-minute calculation is the difference between knowing the deal and guessing.