KOLKATA: West Bengal Chief Minister Mamata Banerjee today questioned the government's decision to give income tax exemption on deposits by political parties in old 500 and 1,000 rupee notes, saying the timing of the announcement shows that there may be "an ulterior motive".Her statement came a day after Revenue Secretary Hasmukh Adhia stated that political parties depositing old 500 and 1,000 rupee notes in their accounts will be exempt from income tax provided the donations taken are below Rs 20,000 per individual and properly documented."They need to clarify that #DeMonetisation means it is #DeMonetisation for all. Same rules for everyone. If 500/1000 are illegal tender, then how are they trying to show that there is a division btwn common people & political parties?" Banerjee said in a series of tweets."Even the timing of these statements show that there may be an ulterior motive. Is there a motive? Are they trying to give a hidden message to cadre of one political party? Why these confusing and misleading statements now? They must clarify," she said."It is most unfortunate how there are confusing and misleading statements coming from senior govt officials," said the Trinamool Congress chief, who has been vociferous in her opposition to the Centre's demonetisation move.In a press conference yesterday, Adhia had said the government is not tinkering with the tax exemption available to political parties and they are free to deposit old 500 and 1000 rupee notes in their bank accounts. But these deposits will, however, be subject to the condition that individual donations taken in cash do not exceed Rs 20,000 and are properly documented with full identity of the donor."If it is a deposit in the account of a political party, they are exempt. But if it is deposited in individual's account then that information will come into our radar. If the individual is putting money in his own account, then we will get information," he had said.