The Federal Perkins Loan Program. which is a relatively small program.
Next, you need a "qualifying" repayment plan. All of the "income-driven repayment plans " are qualifying plans for Public Service Loan Forgiveness. So is the 10-year Standard Repayment Plan, but if you're on that repayment plan, you should switch to an income-driven repayment plan straight away. or you will have a drastically lower loan balance left to be forgiven after you meet all of the criteria.
If you're consolidating your loans, you can apply for an income-driven repayment plan in the consolidation application. but if you don't, you will be placed on the Standard Repayment Plan for Direct Consolidation Loans. which is almost never a qualifying repayment plan for Public Service Loan Forgiveness. If you already have Direct Loans, you can submit an income-driven repayment plan application on StudentLoans.gov .
Lastly, you need to make "qualifying" payments—120 of them. A qualifying payment is exactly what you would expect it to be. You get a bill. It has an "amount due" and it has a "due date". Make the payment in that amount by the due date (or up to 15 days after), and the payment is a "qualifying payment". If you make a payment when you're not required to—say, because, you're in a deferment or you paid your student loan early—then that doesn't count. But if you reliably make your payment every month for 10 years, you should be okay. The best way to ensure that your payments qualify is to sign up for automatic payments with your loan servicer .