California Code, Corporations Code - CORP § 410

(a) Every subscriber to shares and every person to whom shares are originally issued is liable to the corporation for the full consideration agreed to be paid for the shares.

(b) The full agreed consideration for shares shall be paid prior to or concurrently with the issuance thereof, unless the shares are issued as partly paid pursuant to subdivision (d) of Section 409, in which case the consideration shall be paid in accordance with the agreement of subscription or purchase.