India, April 24 -- Imagine a restaurant packed to the brim on a busy Friday night - orders flying in, tables turning quickly, and the billing counter barely getting a moment to breathe. Customers pay for their orders, collect a printed receipt and leave well-fed. However, what they do not suspect is that restaurants could quietly delete some of those bills from their systems hours later.

It is precisely this trail that tax officials are following. Sleuths from the GST and income tax departments have raided nearly 100 restaurants across 45 cities since the end of last year, and what they have found is not unaccounted-for cash but a far more systemic pattern of tampering with or completely erasing sales. 

Sources from the tax departm...