New Delhi: Tax officials must avoid "fishing inquiries" into goods and service tax (GST) related matters, specify the nature of the investigation in formal letters to designated company officials, and avoid vague expressions in letters and summons, under new guidelines from the Directorate General of GST Intelligence (DGGI).

This is part of the authority's effort to put in place procedures that are in sync with ease of doing business, said two persons informed about the development, one of them a government official.

The guidelines, a copy of which was seen by Mint, said that when starting a probe or seeking information which are based on records or are reflected in the statutory books of account or filings, then letters should be written to the designated officers of the business instead of issuing summons.

This procedure applies in the case of a listed company, or state-owned enterprise, government department or agency or any other authority, the guidelines said.

Such letters have to specify the reasons for investigation and the legal