September 28, 2003
Under Proposition 13, new construction, which can include actions such as
demolition, is subject to reappraisal in almost all instances. The completion of
construction triggers a supplemental assessment for the value added or
subtracted from the prior value of the property.
There are, however, times when new construction does not result in a
supplemental assessment at the time of completion. The most common exclusion is
available to owners of property who are building one or more residences for sale
rather than their own use. The owner needs to file a claim form with the
assessor prior to or within 30 days of commencement of construction stating that
the property will not be occupied, rented or leased prior to sale to the
With this claim on file, the assessor's office enrolls construction in progress
values if the construction period extends over one or more Jan. 1 lien dates.
The final supplemental for new construction is held until the property sells and
is then combined with the supplemental for the purchase of the property.
A person building one residence for sale, sometimes known as a speculative or
"spec" house, can claim this builder's exclusion as can a large corporation
building 500 homes in a new subdivision.
Another common exclusion from supplemental assessment is the construction needed
to restore a property after a calamity or other disaster. The property must be
restored to the substantial equivalent of its pre-disaster condition to qualify
for this exclusion. Additions or upgrades to the property beyond restoration
would trigger a partial supplemental assessment for the added value of those
Other exclusions from supplemental assessment occur less frequently. Active
solar systems are excluded from supplemental assessment, as are the addition of
fire sprinklers and other fire suppression systems to an existing building. If a
property owner is modifying an existing residence to provide accessibility for a
disabled person, the accessibility construction is excluded from supplemental
Finally, under certain circumstances, seismic retrofit work on an existing
building can be excluded from supplemental assessment or postponed from
supplemental assessment for a 15-year period.
Should you have any questions please contact Napa County Assessor John Tuteur at
253-4459 or by e-mail at email@example.com. Articles on new construction,
supplemental assessments, calamity exclusions among many others can be found at
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