California Civil Code Section 5600 (b) which is part of the Davis-Stirling Act reads as follows: 

An association shall not impose or collect an assessment or fee that exceeds the amount necessary to defray the cost for which it is levied. 

Consequently, an association cannot charge an arbitrary move-in or move-out fee without violating the law. Notwithstanding, an association can demand that a refundable deposit be paid to cover the possible cost of damage to the common area when someone moves in or out, assuming the association's CC&Rs or operating rules permit the collection of such a deposit. Many homeowner associations adopt an operating rule to address this issue.