Is LTA payable for completed months only or on pro-rata basis till the last working day?

I was with a company for little less than 2 years. As part of my full and final settlement, I was told that LTA, which was part of my CTC, that it is payable for completed months only. Is LTA payable for completed months only or on pro-rata basis till the last working day? Please advise.

The concept of CTC has not standing in law, so none of the laws have any impact on it, except to some extent contract act.
It is therefore left to the company's discretion how much to give. Most companies would not even give the LTA as a part of the F&F. So you should simply accept the "completed months" working and be thankful you are getting it.