California Code, Health and Safety Code - HSC § 1407

(a) Any licensee desiring to voluntarily surrender his or her license for cancellation or temporary suspension shall notify the department in writing as soon as possible and, in all cases, at least 30 days prior to the effective date of cancellation or temporary suspension of the license.

(b) Any license placed in temporary suspension pursuant to this section may be reinstated by the department within 12 months of the date of the voluntary suspension on receipt of an application and evidence showing compliance with licensing requirements.