The PLUS loans that some graduate students have taken out in recent years are eligible. Perkins Loans and many federal loans for people entering health professions are not eligible. And again, private student loans are not part of the mix here either.

Also, if you’re in default on the loans, you won’t be eligible.

Q. How do I know what kind of loan I have?

A. Don’t be embarrassed to ask, since many people have forgotten or never knew in the first place. Call your lenders now and ask them. The Education Department plans to inform all eligible borrowers in January as well. If you haven’t heard from them by the end of that month, call them at 1-800-4FEDAID (1-800-433-3243) and ask.

Q. Is there a limit to the number of federal loans I can consolidate?

A. No.

Q. What will I save if I consolidate under the new program?

A. It depends, and the formula for calculating your new interest rate is complex.

First, you’ll subtract 25 basis points (a quarter of a percentage point) from the interest rate of your federal loan that a bank or other lender originated. You can also subtract another 25 basis points for both those bank loans and any loans that came from the federal government directly if you agree, once the loans are consolidated, to let the federal government (which will be the new lender of record) pull the payment automatically from your bank account each month.

The new rate will then be a weighted average of the two (newly discounted) rates from the two different types of loans, based on the balances of each loan.