Value addition regarding

1). If his business is in net loss than in this situation it can be happen, not required to pay any tax in cash.

2). or otherwise business is in Profit, but intial investment in capital asset is high, for which he has taken ITC Credit on capital goods and using that ITC Including ITC on regular purchase to set of output liability, so in that case also it's possible.

@ Sagar ji, but the taxpayer is a dealer, hence, no question of ITC on capital goods arises.

If taxpayer is dealer, than it happens in case he has a more purchase as compare to sale, so increase in stock year by year.

or as per point no.1 mentioned above.

If there is no increase in stock and also have a profit in books of account that it's looks suspicious.

1. It's cannot be possible in accounting system . check his purchase & sale . as in case of practice of under billing the ITC will always be the excessive.

2. Or he might be taking the bulk purchase in end of month.