Louise: actually what she is doing is illegal. Even if you had paid the $8, she is required to report that income to the government and you have the right to claim it. If you had entered an agreement to pay less with no reciept, you would have been participating in defrauding the government. Tell her that you are going to claim it with or without a reciept and that you will report her to the government. I'm pretty sure she won't like the prospect of being audited!