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Frequently Asked Questions

The following are questions we often receive from Merced County property owners. For specific information, please call us at (209) 385-7592, visit our office, or e-mail us.

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What are "supplemental" property taxes?

"Supplemental" taxes are additional secured taxes that are due when property undergoes a change in ownership or new construction. The additional tax is owed because the County Assessor is required to immediately adjust the January 1 value to reflect the new value of the property. Adjusted for the number of months left in the fiscal year, the supplemental tax bill represents the tax due on the difference between the old and new values.

How are the supplemental tax amounts determined?

The difference between the new value and the old January 1 value is multiplied by a proration factor. The proration factor is the percentage of months remaining in the fiscal year. This result is then multiplied by the tax rate (usually 1% plus voter approved indebtedness) to determine the supplemental tax amount due.

When should I expect my supplemental tax bill(s)?

Most supplemental bills are mailed within nine (9) months after a change in ownership or new construction. You should receive a Notification of Supplemental Assessment approximately sixty (60) days before the bill is mailed.

Why did I receive more than one supplemental tax bill?

You may receive more than one supplemental tax bill, depending on when you purchased your property or completed new construction. Because the secured property taxes are based on the January 1 value and cover a fiscal year, your purchase/construction date may effect the calculation of the taxes for two fiscal years. For example, if you purchased property in February 1998, your purchase would effect the 1997/98 fiscal year taxes (February 1998 through June 1998) and the 1998/99 fiscal year taxes (July 1998 through June 1999). The latter fiscal year is effected because the value would have already been established by the Assessor on January 1, 1998, prior to the purchase/construction. Therefore, the taxes calculated for 1998/99 would also have to be adjusted by a supplemental bill to reflect the increased value.

When is the supplemental tax due?

The supplemental tax is due upon the mailing of the bill. It is payable in two installments.

When does the supplemental bill become delinquent?

The supplemental bill is payable in two installments, like the secured bill. The delinquent dates of the installments depend on when the bill is mailed. A supplemental tax bill mailed between July and October carries a first installment delinquent date of December 10 and a second installment delinquent date of April 10. Supplemental bills mailed between November and June carry a delinquent date based on the month in which the bill was mailed—the first installment is delinquent the last day of the month in which the bill was mailed. The second installment is delinquent four (4) months later. For example, if a supplemental tax bill is mailed in February, the first installment delinquent date would be March 31 and the second installment delinquent date would be July 31.

If I don’t pay on time, will I be charged a penalty?

Yes. If your payment is not received or postmarked by the delinquent dates, the penalty amounts are the same as secured taxes: First installment penalty=10% of the first installment amount. Second installment penalty=10% of the second installment amount, plus a $55 cost fee.

When should I mail my payment to avoid penalties?

When you mail your payment, your payment envelope must possess a United States Postal Service postmark on or before the tax delinquent date in order to avoid the delinquent penalties.

Is a private postage meter date the same as the United States Postal Service postmark?

No. California law requires the Tax Collector to accept the US postmark, not a private meter date, as the date of payment.

Can payments be postmarked on the deadline date?


Can I pay my supplemental property tax bill with my credit card?

Yes. You can pay with your credit card on-line, or by telephone at 1-866-890-4105.