Who Pays Delinquent Taxes on Foreclosed Properties?

Ok you tax experts out there.  I have this simple question that might not be so simple.  I am representing the buyer on a foreclosure condo.  The taxes are delinquent from the previous owner.  Is my buyer now responsible for those taxes or is it the responsibility of the foreclosing bank? 

I was under the impression that as soon as the lender foreclosed, they assumed all tax liabililties for that property.  I asked my broker but his answer was "Its in the contract".  Does anyone have a simple explanation for this?

Thanks in advance for your time.