For initial installations (new SAP customers), the new G/L is active by default in mySAP ERP. SAP advises that customers with new installations use the new G/L. These customers can still use the classic G/L if they prefer, but this may cause difficulties for future G/L migration projects. If existing customers want to use the new G/L, they have to activate it. You can activate the new G/L by following the IMG menu path Financial Accounting>Financial Accounting Global Settings>Activate New General Ledger Accounting or by transaction code FAGL_ACTIVATION. Make sure to select the New General Ledger Accounting Is Active check box.
During a release upgrade, the classic G/L (totals table GLT0) remains active at first. You can hide the old conventional G/L configuration menu by running program RFAGL_SWAP_IMG_OLD.
Activating the new G/L results in system-wide changes to the application menu, screens, and customizing paths. For example, a new configuration menu path appears in the IMG. However, new G/L migration is more than a technical transfer, so you should consider it a separate project. Your migration approach depends on the existing and target design of your G/L. Based on the complexity level, you may find it a simpler solution or more complicated solution leading to conceptual changes.
For example, if your current G/L design does not include parallel ledgers or account solutions for the parallel valuation,you can use the simple migration solution. However, the migration project becomes more complicated if, for example,you use an existing classic G/L with PCA, have an account approach for parallel accounting, or the target design can accommodate an account or parallel ledger approach with or without a split. These examples are only a fraction of possible finance architectures. As a best practice, you should complete a careful analysis on the existing finance processes and you should carefully determine the new G/L scope.