Hra calculation

I have to do the HRA Calculation of a Central Government organisation.The HRA calculation is based on Salary(Basic +DA+Commision as a % of Turnover).However in this formula, DA is taken only if its a part of Retirement benefits.

In my client's case, The Basic amount of a retirement benefit-PENSION is arrived at excluding DA  BUT the DA is added later to this Basic pension amount whiile calculating total pension.

MY QUERY:

Is DA to be included while calculating HRA?