Reserve Bank of India Deputy Governor Rakesh Mohan said that despite a good economic growth the tax-GDP ratio has come down during the last 10 years.

"The GDP has been around six per cent in the last decade and as income increases the tax-GDP ratio ought to go up, but it has not happened", Mohan said, while launching the multi-banking system for collection of central excise duties and service tax in Mumbai and Thane on Thursday.

This phenomenon was not easy to understand except that tax evasion must have gone up instead of coming down, he added.

Mohan said the process of paying taxes has become "painful" even to those who were willing to pay and in this context the multi-banking system could help it make easier for taxpayers and collectors.

Principal chief controller of accounts, Central Board of Excise and Customs, H Prabhakar Rao said Punjab National Bank, Bank of Baroda, Canara Bank and Central Bank of India have been added to the existing five banking entities for excise duty collections.

With this addition, the total of branches involved in the activity would double to 340, he said.