Revised Return

Gud eve sir/madam ...

Usually we used to make vat returns monthly monthly to the commercial tax department later if we found any mistakes we vl do revised returns f that particular month .That revised returns possible only before 6 months beyond we cant but in tax audit case we vl make vat audit nd rectify now my querie is if a client not come under tax audit if he wants to revised his returns beyond 6 months wat is d option left with him