In a major relief to GST taxpayers, the government has decided to cap the maximum late fee for Form GSTR-3B at Rs 500 per return for the tax period July 2017 to July 2020. The reduced fee will be levied only if returns are filed before September 30, 2020, the CBIC said on Friday. Late fees will be nil if there is no tax liability. GSTR-3B is a monthly self-declaration to be filed by a registered GST dealer. GSTR 3B is a consolidated monthly return filing form for the payment of the net liabilities i.e. output tax less input credit.