What's the meaning of "collection of unpaid tabs" in Tsukimonogatari episode 3?
At a bar, you can put something 'on your tab', which is a way of saying you'll pay it later (usually next time you come to the bar) which when you do pay later, can be known as 'collecting a tab'

What Araragi is saying is that all the things he has been putting off have come back looking for resolution at the same time.