Disposable income is Gross Income minus Taxes. A 2 parent family with 2 kids making the same as a DINK couple would have a lower tax burden and more disposable

Disposable income is Gross Income minus Taxes. A 2 parent family with 2 kids making the same as a DINK couple would have a lower tax burden and more disposable income, but the DINK couple almost certainly has more discretionary income, which money left after paying for necessities like housing, food, and medical care.