Rule 6(3) of cenvat credit rules

Our company is Partnership firm dealing in paperboards. There are only 2 areas whereby we were paying service tax i.e. service tax on foreign commission earned and on transporters.   And we have taken service tax input credit on expenses incurred & service tax paid on such expenses.  Our other majority business was purely on VAT/Excise etc.  We would like to know whether Rule 6(3A) of Cenvat Credit Rules, 2004 applicable to us or not. If yes, why?