There are several ways (technical and functional) that can be used to default values in PA infotypes. Here we will discuss briefly about each of them and then the detailed explanation is provided in the separate SCN docs.
1. Using User exit/ BADIs
2. Using Dynamic Actions (T588Z)
3. Using Features
1. Using User exit/ BADIs: Enhancement framework can be used to default values in infotype with the help of core coding. Two type of enhancement can be used.
a. User Exit: Transaction CMOD can be used to default values in PA infotypes by using enhancement PBAS0001 function modules. This is well documented in User Exit to Default values in PA Infotypes
b. Business Add-Ins: Transaction: BADI HRPAD00INFTY can be used to default values in PA infotype againusing SE19 tcode. Complete documentation is available in document BADI to Default values in PA Infotypes
2. Using Dynamic Actions (T588Z): Dynamic action is used to change the sequence of infotype that are triggered while performing any action in Infotypes and changes the normal sequence of Infogroup based on certain conditions (conditions will be again configured in the Dynamic action table T588Z), we can use Dynamic action to also default values of the triggered Infotype in the dynamic action. V_T588Z is the view that will be used to maintain dynamic action table T588Z and thus to configure dynamic action (via sm30). Detailed explanation of the same is documented in Dynamic Action for technical consultant
3. Using Features: We can use tcode PE03 and the already specified feature by SAP HCM to default the values in Infotype screen. This is as demonstrated in the document. Using Feature to Default values in Infotype (Programmatically)