How to Define Posting Period Variant

Enter the Transaction code SPRO in the SAP Command Field and Press Enter

In the next screen Select SAP reference IMG

In next screen-"Display IMG"  navigate the following menu path :

SAP Customizing Implementation Guide -> Financial Accounting -> Financial Accounting Global Settings->Document -> Posting Periods -> Define Variants for Open Posting Periods

In the next screen, Press 'New Entries' button

In the next screen, Enter the Following

1. Enter a unique Posting Period Variant Key
2. Enter a Description for the Variant 

After maintaining the above information , Press 'Save' from the SAP Standard Toolbar

In the next screen, Enter the Customizing Request number

You have successfully defined a Posting Period Variant