Short answer

Form 10DB previously served as proof of payment of Securities Transaction Tax (STT) for claiming a tax rebate under section 88E of the Income Tax Act. However, starting from Assessment Year 2009-10, no rebate is permitted under section 88E because STT is now considered a business expense eligible for deduction.

You can use the Tax P&L available on Console to fulfil this requirement. As a result, Form 10DB (PDF) has become obsolete and is no longer required.