It depends on the plan and, for some of the plans, how you and your
spouse file your federal income tax return.
REPAYE Plan
Your loan servicer will
generally use both your income and your spouse's income to calculate your
monthly payment amount, regardless of whether you file a joint federal income
tax return or separate federal income tax returns. However, only your individual
income will be used to calculate your monthly payment amount if you are
separated from your spouse or are unable to reasonably access your spouse's
income. If you filed your last tax return jointly with your spouse, you’ll
provide alternative documentation of your income, such as a pay stub. If you
filed your last tax return separately from your spouse, you can provide your
tax return as documentation of your income.
PAYE Plan, IBR Plan, and ICR Plan
If you and your spouse file separate federal income tax returns, your loan
servicer will use only your income when determining whether you qualify for the
PAYE Plan or the IBR Plan, and when calculating your monthly payment amount
under the PAYE, IBR, or ICR plans. If you and your spouse file a joint federal
income tax return, your loan servicer will use your joint income when
determining your eligibility for the PAYE or IBR plan, and when calculating
your payment amount under the PAYE, IBR, or ICR plans. However, only your
individual income will be used to calculate your monthly payment amount if you
are separated from your spouse or are unable to reasonably access your spouse’s
income. In this case, you’ll provide alternative documentation of your income,
such as a pay stub.
https://studentaid.ed.gov/sa/sites/default/files/income-driven-repayment-q-and-a.pdf
(edited 2-27-17)
