Cal. Civ. Code § 38-12-105

(1) A
landlord shall not take any of the following actions or direct any agent to
take any of the following actions on the landlord's behalf:

(a) 
Charge a tenant or home owner a late fee unless a rent payment is late by at
least seven calendar days;

(b) 
Charge a tenant or home owner a late fee in an amount that exceeds the greater
of:

(I) 
Fifty dollars; or

(II) 
Five percent of the amount of the past due rent payment;

(c) 
Require a tenant or home owner to pay a late fee unless the late fee is
disclosed in the rental agreement;

(d) 
Remove or exclude a tenant from a dwelling or initiate a court process for the
removal or exclusion of a tenant from a dwelling because the tenant fails to
pay one or more late fees to the landlord;

(e) 
Terminate a tenancy or other estate at will or a lease in a mobile home park
because a tenant or home owner fails to pay one or more late fees to the
landlord;

(f) 
Impose a late fee on a tenant or home owner for the late payment or nonpayment
of any portion of the rent that a rent subsidy provider, rather than the tenant
or home owner, is responsible for paying;

(g) 
Impose a late fee more than once for each late payment, except that a landlord
may impose a late fee more than once for a late payment if the total amount of
such late fees does not exceed the amount described in subsection (1)(b) of
this section;

(h) 
Require a tenant or home owner to pay any amount of interest on a late fee;

(i) 
Recoup any amount of a late fee from a rent payment made to the landlord by a
tenant or home owner; or

(j) 
Charge a tenant or home owner a late fee unless the landlord provided the
tenant or home owner written notice of the late fee within one hundred eighty
days after the date upon which the rent payment was due.

(2) A
provision of a lease of a landlord or person acting on behalf of a landlord
that does not comply with the provisions of subsection (1) of this section is
void and unenforceable. A tenant who is aggrieved by an action taken by a
landlord or person acting on behalf of the landlord in violation of subsection
(1) of this section may bring an action for injunctive relief pursuant to
subsection (5) of this section.

(3) A
landlord who violates subsection (1) of this section shall pay to an aggrieved
tenant or home owner a penalty in the amount of fifty dollars for each
violation.

(4) 
Except as described in subsection (3) of this section, and notwithstanding any
other provision of this section to the contrary, a landlord who violates
subsection (1) of this section has seven days to cure the violation, which
seven days begins when the landlord receives written or electronic notice of
the violation.

(5) If
a landlord violates subsection (1) of this section and fails to timely cure the
violation as described in subsection (4) of this section, a tenant or home
owner may bring a civil action to seek one or more of the following remedies:

(a) 
Compensatory damages for injury or loss suffered;

(b) A
penalty of at least one hundred fifty dollars but not more than one thousand
dollars for each violation, payable to the tenant or home owner;

(c) 
Costs, including reasonable attorney fees to the prevailing party; and

(d) 
Other equitable relief the court finds appropriate.

(6) A
tenant or home owner may raise an alleged violation of this section as an
affirmative defense in a forcible entry and detainer proceeding.

(7) A
late fee is distinct from rent, and a rental agreement may not classify a late
fee as rent for the purposes of section 13-40-104 (1)(d).