Assuming you could get every American to agree to that (good luck!) the economy would be massively transformed while everyone stopped spending on every luxury and most necessities. I guess this would require enormous government intervention to prevent all the out of work shopworkers and manufacturers from starving, which might require taking on a bit more debt.

(The serious answer to the original poster's question is that the US economy is not like a household and the debt does not to be paid off, nor will it ever be paid off.)

That's not how it works at all though. It's not really something that is "paid off", it's a stock of bonds that eventually come due, and can be rolled over into new bonds basically forever.

The actual constraints to the issuance of the bonds or money is 1) available natural resources, 2) available labour resources, and 3) inflation (which is usually a result of money issuance or velocity outstripping (1) or (2)).

GDP doesn't measure people's income. It measures capital expenditures and consumption. So it would be a 50% sales tax and 50% tax on capital spending.

> if everybody put half their income towards paying down the debt

You realize how unrealistic that is right?