As well at the 12 months of the current year each book of first entry also has a Month 13, 14 and 15. This is to allow for transactions for the following year while finalizing entries for the year just completed in the accounting software.
Note: The Nominal Ledger is restricted to the 12 months of the current year.
When the Year-End Routine is run all entries made in Months 13, 14 and 15 become the entries in Months 1, 2 and 3 in the new year and are posted to the Nominal Ledger.