What is the penalty for undisclosed cash, gold or investments?

If a person has cash, gold or investments that haven't been disclosed in ITR, a penal tax of 78% (IT of 60%, plus surcharge of 25% on tax and cess of 4% on tax and surcharge) is imposed if they can prove asset's source. The tax can go up to nearly 86% if they aren't able to provide the source.