Cal. Public Contract Code § 10261

(a) Payments upon contracts shall be made as the department prescribes upon estimates made and approved by the department, but progress payments shall not be made in excess of 100 percent of the percentage of actual work completed plus a like percentage of the value of material delivered on the ground or stored subject to or under the control of the state, and unused, except as otherwise provided in this section. The department shall withhold not more than 5 percent of the contract price until final completion and acceptance of the project. However, at any time after 95 percent of the work has been completed, the department may reduce the funds withheld to an amount not less than 125 percent of the estimated value of the work yet to be completed, as determined by the department, if the reduction has been approved, in writing, by the surety on the performance bond and by the surety on the payment bond. The Controller shall draw their warrants upon estimates so made and approved by the department and the Treasurer shall pay them. The funds may be released by electronic transfer if that procedure is requested by the contractor, in writing, and if the department has, in place at the time of the request, the mechanism for the transfer. (b) (1) Notwithstanding subdivision (a), when the director of the department has made a finding prior to the bid that a specified project is substantially complex and therefore requires a higher retention amount than 5 percent, and the department includes in the bid documents details explaining the basis for the finding and the actual retention amount, then payments upon contracts by the department shall be made as the department prescribes upon estimates made and approved by the department. However, progress payments shall not be made in excess of 95 percent of the percentage of actual work completed, plus a like percentage of the value of material delivered on the ground or stored, subject to, or under the control of the state, and unused, except as otherwise provided in this section. At any time after 95 percent of the work has been completed, the department may reduce the funds withheld to an amount not less than 125 percent of the estimated value of the work yet to be completed, as determined by the department, if the reduction has been approved, in writing, by the surety on the performance bond and by the surety on the payment bond. The Controller shall draw their warrants upon estimates so made and approved by the department and the Treasurer shall pay them with funds appropriated therefor. The funds may be released by electronic transfer if that procedure is requested by the contractor, in writing, and if the department has, in place at the time of the request, the mechanism for the transfer. (2) Any finding by the director of a department that a project is substantially complex shall include a description of the specific project and why it is a unique project that is not regularly, customarily, or routinely performed by the agency or licensed contractors.