California Revenue and Taxation Code
If the board is dissatisfied with the report or return filed by any person, it may compute and determine the amount to be paid upon the basis of any information available to it. One or more deficiency determinations may be made of the amount of tax due for one or for more than one month.
The amount of the determination, exclusive of penalties, shall bear interest at the modified adjusted rate per month, or fraction thereof, established pursuant to Section 6591.5, from the date the amount of the tax, or any portion thereof, should have been reported until the date of payment.
In making a determination the board may offset overpayments for a month or months against underpayments for another month or months and against the interest and penalties on the underpayments.
If any part of the deficiency for which a deficiency determination is made is due to negligence or intentional disregard of this part or the rules and regulations adopted under this part, a penalty of 10 percent of the amount of the determination shall be added thereto.
If any part of the deficiency for which a deficiency determination is made is due to fraud or an intent to evade this part or the rules and regulations adopted under this part, a penalty of 25 percent of the amount of the determination shall be added thereto.
The board shall give the person written notice of its determination. The notice shall be placed in a sealed envelope, with postage paid, addressed to the person at his address as it appears in the records of the board. The giving of notice shall be deemed complete at the time of deposit of the notice in the United States Post Office, or a mailbox, sub-post office, substation or mail chute or other facility regularly maintained or provided by the United States Postal Service, without extension of time for any reason. In lieu of mailing a notice may be served personally by delivering to the person to be served and service shall be deemed complete at the time of such delivery. Personal service to a corporation may be made by delivery of a notice to any person designated in the Code of Civil Procedure to be served for the corporation with summons and complaint in a civil action.
Except in the case of fraud, intent to evade the tax, or failure to make a report or return, every notice of a deficiency determination shall be given within three years after the 25th day of the month following the month for which the amount should have been paid or the report or return was due, or within three years after the report or return was filed, whichever period expires later. In the case of failure to make a report or return, the notice of determination shall be mailed within eight years after the date the report or return was due.
In the case of a deficiency arising under this part during the lifetime of a decedent, a notice of deficiency determination shall be mailed within four months after written request therefor, in the form required by the board, by the fiduciary of the estate or trust or by any other person liable for the tax or any portion thereof.
If before the expiration of the time prescribed in Section 30207 for the mailing of a notice of deficiency determination the taxpayer has consented in writing to the mailing of the notice after such time, the notice may be mailed at any time prior to the expiration of the period agreed upon. The period so agreed upon may be extended by subsequent agreements in writing made before the expiration of the period previously agreed upon.