That depends, I think, entirely on the debt collector being sold to. I've had medical debt sold to debt collectors that was there for years as I went through b

That depends, I think, entirely on the debt collector being sold to. I've had medical debt sold to debt collectors that was there for years as I went through back and forth figuring out whether it was valid, and it never showed up on my credit report, nor did various others where a couple of medical providers I used for a while had a bad habit of selling my bills to them before my insurance paid them in full for it.