1. MISMATCH IN TDS DATA: If any details of TDS given by tax payer do not match with data with Income Tax Department, then tax refund of such tax payer will be delayed and he will be issued a notice regarding providing proof of the details given by him.
2. WRONG ADDRESS: Many people provide their current address while filing income tax return. Income tax department has the address given by them at the time of PAN application, so this mismatch can also pose problems in relieving tax refunds. You must update your address as it changes, with Income Tax Department.
3. MISSING BANK ACCOUNT DETAILS: Now Bank account details are mandatory to be given while filing income tax return. If such details are not provided then refund can be delayed. While filing return electronically no one can ignore such details as XML file will not be generated unless all details are given. But such mistake is with manual filing.
4. LATE SUBMISSION OF ITR-V: ITR-V generated while filing income tax electronically, should reach CPC in Bangalore within 120 days of filing return otherwise refund of such return may be delayed. No refund will be relieved unless ITR-V is sent.
5. LARGE NUMBER OF TDS ENTRIES: If there are huge numbers of TDS entries, say 70-80 entries, your assessment may take little longer. So, refund also gets delayed.