Cal. Revenue and Taxation Code § 13810

When the Controller claims that a decedent was domiciled in this state at the time of his or her death and the taxing authorities of another state or states make a like claim on behalf of their state or states, the Controller may make a written agreement of compromise with the other taxing authorities and the executor or administrator that a certain sum shall be accepted in full satisfaction of any and all death taxes imposed by this state, including any interest to the date of filing the agreement. The agreement shall also fix the amount to be accepted by the other states in full satisfaction of death taxes. The executor or administrator is hereby authorized to make that agreement. Either the Controller or the executor or administrator shall file the agreement, or a duplicate, with the authority that would be empowered to determine death taxes for this state if there had been no agreement; and thereupon the tax shall be deemed conclusively fixed as therein provided. Unless the tax is paid within 90 days after filing the agreement, interest shall thereafter accrue upon the amount fixed in the agreement but the time between the decedent’s death and the filing shall not be included in computing the interest.