California Code, Public Contract Code - PCC § 10301

Except in cases when the agency and the department agree that an article of a specified brand or trade name is the only article that will properly meet the needs of the agency, or in cases where the Department of General Services has made a determination pursuant to Section 10308, all contracts for the acquisition or lease of goods in an amount of twenty-five thousand dollars ($25,000), or a higher amount as established by the director, shall be made or entered into with the lowest responsible bidder meeting specifications.

For purposes of determining the lowest bid, the amount of sales tax shall be excluded from the total amount of the bid.