In legal terms, the program is funded not just by today’s payroll taxes, but by accumulated past surpluses — the trust fund. If there’s a year when payroll receipts fall short of benefits, but there are still trillions of dollars in the trust fund, what happens is, precisely, nothing — the program has the funds it needs to operate, without need for any Congressional action.
Alternatively, you can think about Social Security as just part of the federal budget. But in that case, it’s just part of the federal budget; it doesn’t have either surpluses or deficits, no more than the defense budget.
Both views are valid, depending on what questions you’re trying to answer.
What you can’t do is insist that the trust fund is meaningless, because SS is just part of the budget, then claim that some crisis arises when receipts fall short of payments, because SS is a standalone program. Yet that’s exactly what the WaPo claims.
I wonder if the people who want to privatize social security have thought through exactly how bonds held in a 401(k) are different than the trust fund? Perhaps they are more awkward to default (in terms of not paying the bonds) on but governments have raided retirement accounts before. Add in the strange equivocation between "social security" and "social security/medicare" in terms of projecting cost growth (with the second) and targeting the first for reduction.
In general terms, I do not understand why there are such strong objections to income support for people in old age. The program isn't cheap but it widely benefits the majority of Americans (a lot). Why is it such a popular target for debate? Why not debate how high defense spending is relative to the rest of the planet? Or the amazing cost increases in medical care? Why are these not more pressing issues?
I really do not understand because this debate is eating up precious intellectual effort that really needs to be going into comparative effectiveness discussions for medicine.