Puzzled that sizeable sections of eligible assessees are yet to file even the interim summarised return (GSTR-3B) for July and August, the revenue department has instructed field formations to conduct surveys and find out the reasons for the same. Of the 65 lakh eligible taxpayers, only 53.5 lakh (82%) and 46.5 lakh (75%) had filed GSTR-3B \u2014 which entails tax payment \u2014 for July and August, respectively, till last Friday. Government officials say that delay in filing GSTR-3B would have an adverse bearing on filing the comprehensive GSTR-1 return, the deadline for which ends on October 10 for July GST. The deadlines for filing invoice-level returns (GSTR-1, GSTR-2, GSTR-3) have already been extended twice. Even among businesses that filed the interim returns, a large segment (40% in July) paid no tax in cash. Although the government is reconciled to this given that in the initial two months after GST roll-out, the accumulated transitional credit was high and was to be legitimately used. It is another matter that the credit would be allowed in a staggered manner (up to December) to avoid a temporary revenue shortfall. Also, there are players who deal with exempted (zero tax) goods and items outside the GST ambit. But the government feels that the gap between the eligible taxpayers and GSTR 3 B filings is still large and needs probing. \u201cSo far, only 35.5 crore GSTR-1 invoices (for outward supplies) have been uploaded for July and this is much lower than our expectation,\u201d GST Network CEO Prakash Kumar had said on Saturday. GSTN, the IT back-end for GST, had estimated that nearly 80 crore invoices would be uploaded every month, on the basis of a study on VAT assessees in three states. Taxpayers are required to file GSTR-1 by October 10. GSTR-2 (inward supplies) get populated automatically once GSTR-1 is filed. But a taxpayer who fails to file GSTR-1 by the stipulated deadline won\u2019t be able to make use of the window \u2014 October 11-31 \u2014 to file GSTR-2, as both these forms can\u2019t be filed simultaneously. The delay in filing comprehensive returns means that the detection of tax avoidance can\u2019t be carried out through invoice matching, a situation that defeats the basic objective of GST. Although, nearly 95% of GST revenue comes from less than 5% taxpayers, the government needs the data from all eligible taxpayers to analyse the impact of GST more efficiently and accurately, sources said. \u201cEven though 40% of the GSTR-3B returns filed for July have claimed nil tax liability, the details in the return helps us in accurately predicting future GST revenue,\u201d an official said. \u201cThe number of taxpayers claiming nil return was higher for July as many could offset tax liability with available transitional credit,\u201d said MS Mani, tax partner at Deloitte. He added that this number would progressively reduce as transitional credit is exhausted. Nearly 90 lakh taxpayers have registered so far on the GSTN portal including 72 lakh assessees who have migrated from the earlier regime and 15.5 lakh under the concessional composition scheme. However, nearly 6.5 lakh migrants are yet to complete their registration, which makes them ineligible for filing returns. File facts Only 75% of eligible taxpayers for July and 82% for August have filed the interim summarised return, GSTR-3B. While GSTN expected 80 crore invoices month, only 35.5 crore GSTR-1 bills uploaded for July so far. Over 95% GST revenue comes less than 5% taxpayers, but the gap between the total number of GSTR registrants and the returns filed vexes revenue dept. Nearly 40% assessees paid nil tax in cash for July; govt OK with this given transitional credit.