Most of the examples above present a generic use of the noun "income." "income" can be countable or uncountable, but being uncountable does not mean that it will not take any determiner -- if the indefinite article is not suitable, the definite article or a possessive may be used.
Actually, several of the examples above could have taken one of those:
Families might use other resources or their current income to pay for the first few years of college while doubling down on stocks in their 529 accounts to profit from a rebound.
In a Chapter 13 bankruptcy, by contrast, you can get rid of some tax debts that stem from fraud or unfiled returns, but you're expected to pay at least something toward those tax bills from your current income for three years.
Those transactions, criticized at the time because they gave the family deals not available to ordinary shareholders, were intended to maximize the current income for the Chandler family (the Chandler family's current income) while minimizing the family's tax bill and allowing it to diversify its investments.
Ms. Brett cleaned apartments for an extra income.
He would say only that he lost $75 million in his future income.
For further reference, see the Collocations section for "income" here.