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New Construction
Supplemental Assessments
State law requires the assessor’s office to reappraise property upon change in ownership or completion of new construction. The assessor’s office must issue a supplemental assessment, which reflects the difference between the prior assessed value and the new assessment. This value is prorated based on the number of months remaining in the fiscal year, which ends June 30. This is in addition to the regular tax bill. Notices of supplemental assessments are mailed to property owners prior to the issuance of supplemental tax bills.

Completed New Construction
Assessment is only required if the construction is new. Replacements, such as re-roofing, do not require reappraisals. In appraising new construction, the market value of the addition is determined and added to the value of the existing property. The value of the existing property does not change.

Incomplete New Construction
If a construction project is not complete on January 1, the market value of the incomplete construction is determined and added to the assessment roll.

Supplemental Tax Calculation
If the market value is $100,000, supplemental taxes for a property purchased on September 12 and valued at $60,000 would be calculated as follows:

New base year value


Current roll value

- 60,000

Supplemental assessment


Nine months of the year remaining

x 0.75


Approximate tax rate

x 0.0115

Approximate supplemental bill


For more information about new construction or supplemental tax assessment, please contact the assessor's office at (530) 458-0450.