Tempted to borrow from your 401(k) to pay off your bills from Christmas gifts or a winter get-away? Think twice about that. You’ll will pay yourself back with after-tax dollars, which, when you take distributions later in life, you’ll pay tax again on those same dollars. You’ll also be on the hook to pay back the full amount if you leave your job for any reason. Best to save for extras beforehand, then you can really enjoy your splurges worry-free.