Disposable income already considers this, it's an apples to apples comparison.
Are you sure? I mean, really sure?
After all, the link you provided states "Disposable income is the amount of money a household has available for spending and saving after income taxes have been deducted" then goes on to qualify this with "This figure will be the most significant dollar amount because government taxes at the federal and state level are not included in the figure."
You'll note that missing from either of these quotes (or any other rider on that page) is any reference to: adjustments for state funded healthcare; parental leave allowance, or maternity or paternity pay; social security benefits / in work benefits; and so on.
So, I wonder, what is it, in toto, that you think 'Disposable income' covers exactly?