About 10 months back, the Central Government had set up an email ID blackmoneyinfo@incometax.gov.in on which information about black money could be given (see, the news report, here).
Moreover, Director General, Investigation, Income Tax, is the wing of the Income Tax department that deals with investigation into black money and related issues. Contact details of all the offices of the DG, Investigation, Income Tax, spread all over the country, can be seen by clicking on this page; you can search the contact details of the concerned office in your city or state (http://office.incometaxindia.gov.in/investigation/Documents/Investigation.pdf) and contact them.
In addition to this, recently there were media reports (see, here) as per which the Centre is planning to give out cash rewards to the tune of Rs 1 crore to secret informers who provide information to investigative agencies about benami properties. As per this news report, an announcement is expected to be made by October end or first week of November. So far, there is no such announcement. If I come across any such announcement, I’ll update this reply to your question.
Dr. Ashok Dhamija is a New Delhi based Supreme Court Advocate and author of law books. Read more about him by clicking here. List of his Forum Replies. List of his other articles. List of his Quora Answers. List of his YouTube Videos.