Leave encashment during service and at the end of service
Leave encashment during the service and at the end of the service are two aspects to consider. Since leave encashment is not an emolument like salary (basic + DA), it's not a statutory provision in many private sector units. However, in the government sector, there are provisions governing encashment.
In the private sector, many units implement this payment by allowing the surrender of EL/PL only for encashing those days. Some units allow a few days every year, subject to a maximum number of days, while others permit it not every year but as and when feasible. However, most units allow encashment at the credit as part of the Full and Final settlement upon separation due to superannuation, VRS, termination, death, etc., subject to a maximum of, say, 300 or 240 days, as per their service conditions.
Generally, gross salary is taken for computation. The gross salary might include basic pay, DA, HRA, which are payable to employees when they are on EL/PL. The gross salary at the time of encashment is reckoned. I have not come across any unit paying only basic pay. Some units allow encashment linked with LTA. Leave encashment is taxable like salary.