Arizona, where this matters most
Arizona has more age-restricted housing than almost anywhere in the country, which means this mistake is made here more than almost anywhere. Mixing restricted and unrestricted sales does not produce a slightly imprecise value. It produces a value that is wrong in a direction you cannot predict.
Under the federal Housing for Older Persons exemption, a qualifying community can lawfully refuse to sell to households that do not meet its age requirement. Typically at least one occupant must be 55 or older, with limits on younger residents.
That is the whole point. Every other characteristic an appraiser adjusts for — size, lot, pool, garage — changes how much a buyer will pay. Age restriction changes who is permitted to be a buyer at all. It shrinks the demand pool by law rather than by preference.
A market with a legally narrower set of buyers behaves differently. It responds to different pressures, moves on a different cycle, and sits at a different price level relative to the housing around it. None of that is captured by adding or subtracting a figure for “community amenities.”
Every other difference changes what a buyer will pay. Age restriction changes who is allowed to be a buyer. That is a different market, not a different feature.
The surrounding market usually has a wider buyer pool and, in many Arizona submarkets, more families competing for the same square footage. Pull those sales into an age-restricted property and the value tends to come out high — and the listing sits, because the buyers who set those prices are not allowed to buy it.
The reverse, and it is the more damaging one because it looks reasonable. The homes are often the same era, the same builder and physically almost identical — many Arizona master-planned areas sit an age-restricted village directly beside an unrestricted one. A seller gets a number built on the restricted side of the fence, prices to it, and leaves money on the table.
Two age-restricted communities can differ enormously in monthly fees, what those fees buy, whether the golf is included or separate, and how the resale market has held up. The restriction makes them comparable in kind, not in degree. It is the start of the comparison, not the end of it.
This is one of the few places in residential valuation where the right answer is to exclude data rather than to correct it. A smaller set of genuinely comparable sales beats a larger set containing a category error.
Agents who specialise in 55+ inventory generally know all of this by instinct. The problem is rarely the listing agent’s judgement — it is that the tools they are handed do not share it. A website estimate, a price-per-foot pull, or an automated model that never saw the restriction will produce a number the agent then has to argue down, in front of a seller who liked the higher figure.
The fix is a valuation that treats age restriction as a hard filter on which sales are eligible in the first place, and says so on the page where the comparables are listed. Then the conversation is about which homes were used, which is a conversation worth having.