This changes annually based on a Prop 13 or CA CPI tax adjustment.
When the property is sold to a new buyer the prior percentage valuation split between land and improvements are changed. I have not been able to figure out why; however, it seems to go from a prior owner split of 80/20 to a new owner 70/30 split).
In any case, the splits really do not change the final outcome of the total tax. Even though the land and improvements are separated on the property tax bill, both are subject to the same Prop 13 OR California CPI assessment provided by the CA State Board of Equalization, whichever is LOWER.
So, the answer to your â€œlot size valueâ€ question is while an owner maintains possession of the property the only value calculation made for a lot (and improvements) is taking the prior yearâ€™s values and applying either the Prop 13 or CA CPI multiplier. This is also covered in the blog below:
"Estimating Property Taxes in CA"