Every year, the variable rates on federal student and parent loans are adjusted based on the last Treasury bill auction in May.

That auction was today. And the results mean that beginning in July, the new rates on variable-rate loans will be about 3 percentage points lower for the next year.

“This is the biggest drop ever in the interest rates on variable-rate loans,” says Mark Kantrowitz, publisher of FinAid, in an e-mail. “The new rates themselves are the fourth lowest rates in the history of the student loan program.”

If you have a federal Stafford loan or a parent PLUS loan issued before July 2006, then you have a variable rate loan. (Loans made after that date have a fixed rate of 6.8 percent for student loans and 8.5 percent for a PLUS loan.)

And if you have variable rate loans, consider consolidating those loans after July 1, when these new low rates kick in. Your variable-rate loans will be combined into a new single loan at a fixed rate based on these new low rates.

According to Kantrowitz, if you consolidate a Stafford loan while in school or during the grace period the new rate will be 3.625 percent. The rate on a Stafford loan now in repayment will be 4.25 percent. And the rate for a consolidated PLUS loan will be 5.125 percent.

A new grad, for instance, with $20,000 in Stafford loans would save $3,521 in interest over the 10-year life of the loan by consolidating while in the grace period.

Kantrowitz says there is little benefit to consolidating fixed-rate loans.

Also, you may find it difficult to find a lender willing to consolidate your loans. Many have been bailing out of the business during the credit crunch. Kantrowitz says borrowers will likely have to go the Federal Direct Consolidation Loan program.