Month End Processing (MEP) functions as a sum-up of all transactions from the starting of financial period until the time of MEP. This processing is only done for all temp accounts / accounts in the P(L) Statement. As you know, accounts in the P(L) are only for the current year. Revenues generated, Cost of Sales incurred and expenses charged are only for the current financial period. On the other hand, Balance Sheet accounts are called Real Accounts because they accumulates over time.

What happens here is that, as more new transactions are posted into the P(L), MEP needs to be done to add up all the new transactions to derive the final correct total. MEP can be done anytime (not necessarily at the month end). However, it is called "Month End" Processing because users normally generates P(L) at the end of each month. Therefore, the processing is done every month-end, before generating financial statements.

• Accounting > Journal and Ledger > Month End Processing
• Select a PC Centre and click 'Set PC Centre'.
  
• You will see a messages such as this : The system has detected 7 Temporary General Ledger(s) below that has not been transferred / posted to the Profit and Lost Account
• The table below is actually a Trail Balance. All temp and real accounts goes here.
  
• Check to see if the total balance at the bottom match.
  
• Notice that all the highlighted rows are active P(L) temp accounts. Some other P(L) accounts are not highlighted because they were not updated (no new transactions since the last MEP).
• Finally, just click Transfer These Temporary Balances To Profit And Loss Account.

Troubleshoot : If P(L) does not show the correct amount.

Click MEP and complete the steps. The effect of not doing MEP is that some transactions in the GL will not be taken into account in the closing balance, hence, very much under-stated. Then, select the date range up to end of the month before generating financial statements.