If your contract is going to expire and you intend to work until the end of the contract period, the following section of the Employment Act may be applicable and by letting them know a month earlier is good enough as a matter of courtesy. If you intend to terminate the contract in the middle of the contract period, 2 months notice shall be given.
11. Provision as to termination of contracts.
(1) A contract of service for a specified period of time or for the performance of a specified piece of work shall, unless otherwise terminated in accordance with this Part, terminate when the period of time for which such contract was made has expired or when the piece of work specified in such contract has been completed.