What can cause a delay in receiving tax refunds after filing ITR?

Income Tax Department has so far processed 74.44% of verified ITRs, which means over 1.83 crore tax refunds are yet to be processed. This delay can be caused due to discrepancies in the data. ITR-2 or ITR-3 forms moreover take longer time to be processed. Additionally, if refund claim size is large, tax authorities follow rigorous checks, causing further delay.