Cal. Revenue and Taxation Code § 20634

All amounts postponed pursuant to this chapter shall be due if any of the following occurs: (a) The claimant ceases to occupy the cooperative residential unit, or sells or otherwise disposes of shares in the cooperative housing corporation. (b) The claimant dies. However, if the surviving spouse or another person eligible to postpone pursuant to this chapter continues to occupy the cooperative residential unit, then the postponed amounts shall not be due unless such person dies, ceases to occupy the residential unit, or the shares are sold, or otherwise transferred. (c) The failure of the claimant or the cooperative housing corporation to perform those acts specified in the recognition agreement, or the failure of the claimant to perform those acts required by a security interest holder which is senior to the state’s security interest for postponed amounts. (d) Postponement was erroneously allowed because eligibility requirements were not met.