Non-discretionary spending is mandatory spending, aka entitlement spending. Implied in the name 'non-discretionary' is that you can't just cut it without major

Non-discretionary spending is mandatory spending, aka entitlement spending. Implied in the name 'non-discretionary' is that you can't just cut it without major entitlement reform. The point of the article is that without that entitlement reform it's very hard to balance the budget, even with 100% taxes on the 1%.