Default value of the entity

I have a entity attribute in the other appliaction which I am referening in my applicaton whose default value is CurrDate(). So when I am using this antity in to my application it automatically shows the currDate.. But I want to set  date to a input field in to my application which refers  to the entity to CurrDate()+3... How can I do that.

If I understood you correctly, are you asking for this?
AddDays(CurrDate, 3)