ya if your on the rdwl and your forced to work your relief day then you get your choice if you want daca 3
a half a days pay and another day off of management choosing or daca 5 paid time and a half or you can just take a day later off and work your j day
if your not on the relief day work list then it's supposed to be automatic half a days pay and another day off later management chooses but often time they can work with you what day would work best to take off
not all post masters will follow this some will just try to get you to agree to working your j day and give you a day off later with no further compensation and that's wrong , contact your union rep
and if there's a leave replacement available you can get your non j day Saturday off using lwop leave without pay