Hello Mr. Mohan,
Brought forward and carry forward wage types carry the difference of the amount in a particular wage type during retroactive payroll accounting. For all of the basis wage types where such an accounting is necessary, these wage types are automatically created during accounting.
For customer wage types, these wage types need to be created as detailed in the Note 1895407, so that your Net Pay remains consistent during retroactive accounting.
Best Regards,
Aman