The Income Tax Department pays 0.5% monthly interest on delayed refunds. If you filed your ITR by September 16, interest runs from April 1 till the refund date; for late filings, it starts from the filing date.
This applies to TDS, TCS, advance tax and self-assessment (under Section 140A) tax refunds where interest is paid from the later of filing date or payment date. For excess TDS/TCS paid by deductors, interest begins from claim filing date.

