Students

The reason is so simple is that 

If u have to arive at the Correct profit of current year 

Then Outstanding expenses related to previous which is paid in current should be added to the current year profit bcs outstanding expenses are of previous year and it should be paid in previous year but it has not done so and paid in current year bcz of that current year profit get reduced hence to arrive at correct profit of current period first add those expenses which are related to previous year and paid in current year. Similarly for accrued income.