Accounting of Income

Partnership firm has carried out a work during the financial year 2009-10(AY 2010-11).But billed during early 2010-2011. Payments received during the year 2010-2011 but TDS certificate 16A issued by the parties clearly shows payments relate to FY 2009-10. Firm follows Mercantile basis. Return filed with out taking Into account these two bills. Whether revised return be filed taking into account the above two bills?