CA Prob Code Section 9652

(a)

Except as provided in subdivisions (b) and (c), the personal representative shall keep all cash in his or her possession invested in interest-bearing accounts or other investments authorized by law.

(b)

The requirement of subdivision (a) does not apply to the amount of cash that is reasonably necessary for orderly administration of the estate.

(c)

The requirement of subdivision (a) does not apply to the extent that the testator’s will otherwise provides.