Hra exemption possible or not?

First, if someone did not disclose amount of house rent paid by him to his employer, so that form 16 has no mention of it, is it possible for him to claim HRA deduction while filing return? (or claim refund after filing is done?) note that he failed to submit rent receipts to his employer in this case. If answer is yes, then please check if amount of deduction is calculated correctly here :actual rent paid:5000, HRA: 4000, grade pay+ pay in pay band+DA=32000 per month (this amount excludes medical allowances, and HRA). rent paid in excess of 10% basic salary:5000-3200=1800 per month. I consider "per month" since DA does not remain constant throughout year. I guess one can calculate this way and add for 12 months. Is this method correct?