I don't think you understand how this works. It isn't like the US recieves a monthly bill that we need to pay with a "minimum payment" (I can't believe I had to just say that). Think of it like the US as a bank and other countries give us money in the form of a CD. We take their money with the agreement that we will pay them interest in exchange for them keeping their money with us for X number of years. That's a simplistic way of thinking of it.
Also, the reason why there has never been an amendment saying that we need to have a blanaced budget is because during times of a recession we need to spend more in order to get out of it. The alternative is what happened in 1929. Monetary policy is one of the tools that the government has to prevent that kind of situation from happening again. If they can't spend more than they bring in, then their hands are tied and we will go into a downward spiral "feeding frenzy" of recession.
So while I would LOVE to see our government be more fiscally responsible (understatement of the year), what you're proposing would not work at all.
I know that we don't have a "minimum payment" per se, and that most of our debt is on long-term contract rate basis.
Have the sur-tax pay into an account that is used only for the payments of the debt. Have government budgetary funds also pay into this account, for the interest on the debt (minimum payment always = interest-only), and make sure that is a one-way street. When the balance of the "debt" account is greater than the amount of debt that we owe, the sur-tax goes out of effect. If we incur more debt after that, the sur-tax goes back into effect. Pay it off again, back out of effect. Make sense?
You have to admit that if this tax was in the form of an amendment that required 66% to override it, it would be VERY difficult for congress to do so. Also, it would put a stigma on deficit spending. We could still do it if necessary, but would have to start paying down the principal in addition to the interest. Congresscritters would all of a sudden be worried because any of their spending would also foist this sur-tax on their constituents.
I view this as superior to a "balanced budget amendment" because it still allows the flexibility of deficit spending, while requiring that it is paid for in a responsible manner. At the same time, in the long term, it should reduce the debt to zero or near-zero.