As far as I comprehend it every time you endorse private credit it is use. And the "tax" is nothing more than tribute. Therefore, there should be no difference between someone who doesn't work at all (think of a non-working spouse) who uses credit cards compared to their spouse who endorses private credit. Now what if the spouse who works converts to lawful money but the other continues to buy on credit cards, let's say, $40,000 per year. My bet is the IRS will be knocking down their door to collect on use of that private credit. Others can clarify this much better than I, but using credit is the taxable event, and every credit card is backed by the system so therefore it is endorsing private credit when one is used.