I got one before I had really started work! I had been working in Sainsbury’s for a Christmas job for two weeks when I got a letter from HMRC telling me they owed me fifty quid or so. I queried it, and they got all sniffy with me and said it was not possible to adjust payments, so I fed it into my bank and said no more. My wage at the time was about twenty quid, well below the tax threshold, so I found it a bit surprising.