Adding 220 to garage no room in my 125 amp main panel. Subpanel will be 10 ft from main will be removing 3 15amp and 1 20 amp breaker to add 50 amp breaker in its place. I'm I allowed to have splices inside of main panel or will I have to add J boxes for circuits that were transferred to subpanel
Yes, you can have splices in the panel to extend wire to reach breakers.
What you cannot do is have splices where a wire enters the panel, is then spliced to another wire that exits the panel.