Cal. Gov't Code § 7263

(a) In addition to the payments required by Section 7262, the public entity, as a part of the cost of acquisition, shall make a payment to the owner of real property acquired for public use which is improved with a dwelling actually owned and occupied by the owner as a permanent or customary and usual place of abode for not less than 180 days prior to the initiation of negotiation for the acquisition of that property.
(b) The payment, not to exceed twenty-two thousand five hundred dollars ($22,500), shall be based on the following factors:
1. (1) The amount, if any, which, when added to the acquisition cost of the dwelling acquired by the public entity equals the reasonable cost of a comparable replacement dwelling.
2. (2) The amount, if any, which will compensate the displaced owner for any increased interest costs which the owner is required to pay for financing the acquisition of a comparable replacement dwelling. The amount shall be paid only if the dwelling acquired by the displacing agency was encumbered by a bona fide mortgage which was a valid lien on the dwelling for not less than 180 days immediately prior to the initiation of negotiations for the acquisition of the dwelling. All of the mortgages on the acquired dwelling shall be used to compute the payment. The amount shall be computed using the lesser of the principal balance of the mortgage on the replacement dwelling or the outstanding principal balance of the mortgage on the acquired dwelling and the lesser of the remaining term on the acquired dwelling or the actual term of the new mortgage. The present value of the increased interest costs shall be computed based on the lesser of the prevailing interest rate or the actual interest rate on the replacement property. The amount shall also include other reasonable debt service costs incurred by the displaced owner.
  For the purposes of this subdivision, if the replacement dwelling is a mobilehome, the term “mortgage,” as defined in subdivision (h) of Section 7260, shall include those liens as are commonly given to secure advances on, or the unpaid purchase price of, mobilehomes, together with the credit instruments, if any, secured thereby.
3. (3) Reasonable expenses incurred by the displaced owner for evidence of title, recording fees, and other closing costs incident to the purchase of the replacement dwelling, but not including prepaid expenses.
(c) The additional payment authorized by this section shall be made only to a displaced owner who purchases and occupies a decent, safe, and sanitary replacement dwelling within one year from the later of the following:
1. (1) The date the displaced person receives final payment for the displacement dwelling, or in the case of condemnation, the date the full amount of estimated just compensation is deposited in court.
2. (2) The date the displacing agency fulfulls its obligation to make available at least one comparable replacement dwelling to the displaced person.
  However, the displacing agency may extend the period for good cause. Also, the displaced owner and the public entity may agree in writing that the displaced owner may remain in occupancy of the acquired dwelling as a tenant of the public entity on the conditions that the displaced owner shall only be entitled to the payment authorized by this section on the date on which the owner moves from the acquired dwelling and that the payment shall be in an amount equal to that to which the owner would have been entitled if the owner had purchased and occupied a replacement dwelling one year subsequent to the date on which final payment was received for the acquired dwelling from the public entity.
(d) In implementing this chapter, it is the intent of the Legislature that special consideration be given to the financing and location of a comparable replacement dwelling for displaced persons 62 years of age or older.