The Centre and state tax officers are working on guidelines to bring uniformity in documents that are to be submitted for faster processing of GST registration application of businesses who pass on tax credit of over Rs 2.5 lakh a month, a senior official said on Friday. Once agreed to by all states and the Centre, the proposal will be placed before the GST Council, chaired by Union Finance Minister Nirmala Sitharaman and comprising ministers from all states and UTs.