O/s liability

hiii....

my query is tht at the end of the year wen a co closes the books how  are the o/s liabilities supposed to be booked?

for eg: 1.if bill is recieved from a particular party on 31 march?  how will it be accounted 

2.if service is recieved in march but the bill is recieved after april 1st?however the co is certain abt the bill amount.

3.if a particular expense is nt recogniized as liability at the year end?

plz reply asap.

thanks a lot