MD is measured in Kilowatt (kW). It is the highest level of electrical demand monitored in a particular period usually for a month period. Maximum Demand for any month shall be deemed to be twice the largest number of kilowatt-hours (kWh) supplied during any consecutive thirty minutes in that month.​

​MD is the peak load imposed by the customer to TNB system at any point of time. TNB need to cater for this peak load whenever required by the customer. Since electricity cannot be stored there must be sufficient available generation, transmission and distribution capacity to meet the highest demand. MD tariffs are structured to reflect the time of day it is used. For these reasons most tariffs for larger users are designed to encourage customers to control their electricity demand at daytime peaks. For example, lower night rate electricity encourages the transfer of daytime usage to the night period. The MD charge is being practiced by almost all utilities in the world.

MD is the highest level of electricity demand recorded by TNB meter during a 30-minute interval in a month. The amount charged to customer is based on the recorded MD in kW multiplied by the respective MD rate. For example, the amount payable by a Tariff C2 customer registering 100kW of MD for a particular month is RM4,510 (100kW x RM45.10/kW).​

TNB imposed MD charge to its large customers, those at medium and high voltage level. The MD charge component is necessary to take into account the peak load imposed to the system by these customers. Waiving this MD charge will result in very high energy rate and does not encourage customers to use electricity efficiently. However, those small customers at low voltage level are only imposed energy charge as their peak load requirement is low.​

Few activities could be carried out by customers that assist in reducing MD charges such as:

 
• Practicing demand side management such as peak shift i.e. shifting their peak operation/consumption to off peak period as MD charges is not applicable during off-peak period for customer with peak/off-peak tariff
 
• Opting for any promotional scheme offered by TNB relating to MD such as Sunday Tariff Rider Scheme (STR).
 
• Starts your motor/equipment in stages or during off-peak period