Why we exclude amount of * year ?

Mr.C.A (ipcc) (173 Points)

27 November 2011  

why we exclude amount of previous year ? for example :  Ascertain the amount of stationery debited to Income and expernditure for 31st dec 05

1) creditors for stationery on 1-1-05

2) stock of stationery on 31st dec 05

 

we exclude / deduct stock of stationery coz this amount for future ?...is it so