Defaulting on a student loan means failing to repay the loan according to the terms agreed upon in the loan agreement. For most federal student loans, this occurs when you have not made a payment for more than 270 days (about 9 months) and have not made any arrangements (such as deferment or forbearance) with your loan servicer. When you default on a student loan, serious consequences can follow, including:

• Losing eligibility for loan deferment, forbearance, repayment plans, and additional federal financial aid.
• Being required to repay the entire unpaid loan amount immediately.
• Being denied certain types of employment or professional licenses.
• Your loan may be turned over to a collection agency, leading to extra fees, charges, and collection costs.
• Wage garnishment without a court order.
• Federal and state tax refunds being withheld and applied to your debt.
• Your credit score being damaged, making it harder to qualify for credit cards, loans, insurance, and housing.
• Potential ineligibility for federal benefit programs and suspension of professional licenses.

In short, defaulting means you have seriously failed to meet your loan payment obligations, leading to legal, financial, and credit consequences that can affect you for years.