AssessCheck

The decline-in-value reduction

A decline-in-value reduction is the one reason a California assessed value can move by much more than the 2% everyone associates with Proposition 13 — in both directions. It comes from Proposition 8, passed later in 1978 and codified at section 51(a)(2) of the Revenue and Taxation Code, and it is temporary by design. This page is about that rule on its own; the base year value it is measured against is on the Proposition 13 page.

What creates a decline in value

The test is a comparison, not a judgment about the market in general. If the property’s market value on the January 1 lien date is less than its adjusted base year value for that year, the assessor enrolls the lesser of the two figures. The adjusted figure — the base year value grown each year by the lower of the California CPI change or 2% — is what it is compared against, not last year’s assessed value.

So a property can be in decline-in-value status in one year and out of it the next without anything happening to the property. What moves is the market value on the lien date, and the comparison is made fresh every January 1.

Why the reduction is temporary, in the statute’s own terms

Subdivision (e) of section 51 is the part that surprises people. After a reduction under (a)(2), the property is reappraised annually at full cash value until that figure exceeds the value it would have had under (a)(1). While it is in that status, an increase above 2% in a single year is not a mistake and not a loss of the reduction — it is the rule working. The same subdivision also says the assessor may not condition the reappraisal on the filing of an assessment appeal, so restoring the value does not depend on whether you protest it.

What the temporary reduction can never do is push the assessed value above the existing factored base year value. Absent a change in ownership or completed new construction, that figure remains the ceiling — which is also the reason a decline-in-value property usually has a lower assessment than a neighbor with the same market value and a later base year.

Worked example (illustrative)

Made-up round numbers, chosen to show how the two figures interact — not a valuation, not your property, and not a prediction.

  1. The two figures: the base year value is $400,000, and after years of annual adjustments the factored base year value for the year in question is $588,000. That second number is what the 2% factor applies to, and what the market value is compared against.
  2. A year in decline: the lien-date market value is $575,000. It is less than $588,000, so the assessed value is $575,000 — the lesser of the two.
  3. The next year, the market falls further: market value $540,000, so the assessed value is $540,000. That is a 6.1% decrease in one year, and no rule prevents it. The 2% figure governs how fast the factored base year value grows; it does not put a floor under the assessed value.
  4. Then the market recovers sharply: market value $610,000 against a factored base year value of $612,000. Because the market figure is still the lower one, the assessed value becomes $610,000 — a 13% increase in one year, still lawful, and still below the ceiling.
  5. And then the decline-in-value status ends: market value $650,000. The factored base year value for that year is $624,000, so the assessed value returns to $624,000 — not to $650,000. The property is back on the Proposition 13 track, growing from there by the lower of the CPI change or 2%.

What this tells you: if your assessed value fell and then jumped, and there was no sale and no new construction, decline-in-value status is the usual explanation, and the number to compare against is the factored base year value — which appears on your notice or is available from the assessor.

What it does not tell you: whether the market value the assessor used is right. That is a separate question, argued to your county’s assessment appeals board, and the appeal page covers it.

Where to go next

Sources