Question: I received a medical bill of $150.00 and I made a payment of $149.99 (just as an experiment) so technically I own the clinic $0.01.

I am curious what will happen to this tiny debt.

1. It will cost them more money than the debt itself to send me another bill. In this case, will they keep sending me bills anyway?
2. Will they eventually sell this debt to a collection agency? Will any collection agency bother to buy such a small bill? If so, at what price?
3. Will this unpaid tiny bill eventually affect my credit score?
4. What will most likely happen to this unpaid bill? What can theoretically happen?

Answer: 
Logically, the clinic will not put effort into pursuing the debt unless the payment terms allow them to tack on a more substantial amount, such as a late fee that's independent of the original amount owed. In that case, eventually late fees (and interest on them) could snowball.

Even without a late fee, you could still receive further bills and a hit to your credit report, because it may not have been worthwhile to program in exceptions to the automated processing to skip actions for very small amounts. [In particular](https://www.creditcards.com/credit-management/will-small-unpaid-balance-hurt-my-credit-score/):

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> A missed payment, even on a small balance, will hurt your score. But a tiny delinquency won’t hurt as much as a big one...
> 
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Another likely scenario is that, if you go back to the clinic, your account will show a balance of at least .01. If you receive identical service your next bill will be 150.01 plus any late fees. This may include not this particular clinic, but those businesses affiliated with this one.

Some companies will enact a minimal late fee, and such could add real dollars to the bill.