California Assessment Calculator

New Construction

New construction is defined as significantly changing or adding to land or buildings. This includes major renovations or changing how a property is used. The Assessor’s Office identifies new construction by reviewing building permits issued by the county or city, field inspections, and analyzing aerial photos. New construction is assessed using the building cost data from the California Board of Equalization’s Assessors’ Handbook Section 531 (AH 531), not the cost paid for new construction. If new construction is in progress over January 1, partial value will be added for the partially complete construction. The full assessed value will be added upon completion and result in increased property taxes.

Substantially Equivalent to New (SEN)

While the AH 531 is typically used for valuing new construction, exceptionally extensive construction projects may be classified as Substantially Equivalent to New (SEN). The SEN designation signifies that the entire building will be reassessed as if newly built. This occurs when most of the original structure is removed or replaced, essentially creating a new building in terms of its overall condition. Examples of SEN construction include but are not limited to significant framing changes, complete building remodels, doubling the square footage, and adding a second story. As every property is unique, the determination of SEN status is made on a case by case basis.

Exclusions

Not all new construction is subject to assessment. Certain improvements are excluded such as rebuilding after a disaster, seismic retrofitting, active solar energy system installations, and modifications to improve accessibility for individuals with disabilities. Additionally, routine maintenance and repairs are not considered new construction and therefore not subject to assessment. Similarly, typical remodeling projects, which are primarily cosmetic in nature rather than structural, are generally excluded from assessment unless new square footage or fixtures are added, or the scope of work is so significant that it meets the criteria for SEN construction.

Appraisal Approach

The California Assessment Calculator utilizes the cost approach, based on data from the California Board of Equalization’s Assessors’ Handbook Section 531 (AH 531). The cost approach estimates the value of a property by calculating the cost to rebuild it. While the cost approach is suitable for new construction, the sales or income approach are generally preferred when sufficient market sales or income data is available.

Building Costs

The California Assessment Calculator uses building costs, specifically “D” type construction, incorporating location and mountain adjustments. Single family building costs exclusively utilize modern post 1990 building costs. For simplicity purposes, some additive costs have been combined. Additionally, new bathroom additive costs are derived from 2-3 units multifamily additive costs.

This Calculator Does Not Include

• Manufacturing building costs
• Garage conversion credit
• Multiple quality class selections
• All additive costs
• Depreciation
• Compact costs
• Adjustments for:
  • Local cost differences
  • Superior and inferior areas
  • Mountain slopes
  • Third and upper floors
  • Changes in building costs since the annual data publication of the AH 531

County Area Boundaries

The county area map boundaries displayed are approximate. For precise legal boundaries, refer to the boundary descriptions provided in the AH 531.

County Variation

Although the AH 531 provides a basis for valuing new construction, variations in county practices can lead to differing valuations. Notably, counties may prioritize different valuation approaches. Moreover, not all counties utilize the full range of quality classifications and some may apply single family building costs uniformly across all building types. Lastly, counties may have differing policies regarding credit for converting garages and partially covered areas into livable space.

Data

The data used in the California Assessment Calculator is derived from the California Board of Equalization’s Assessors' Handbook Section 531 (AH 531). Unlike other published cost data, the AH 531 includes entrepreneurial profit and is intended for tax assessment purposes. While every effort has been made to accurately transfer this data to the calculator, some discrepancies may exist due to input errors. The developer of this calculator assumes no responsibility for any inaccuracies.