If you add in future liabilities, you have to add in future tax income. To do otherwise would be like looking at all your potential bills for food, and not counting your expectation that you would be able to work to pay them.
Of course Congress could change the SS/medicare/medicaid liability tomorrow, by legislation, and darned well should.
They could also change the tax rates tomorrow, and shouldn’t raise them.
If you add in future liabilities, you have to add in future tax income.