Sen. Rand Paul says he’s fulfilling a campaign promise by giving back $500,000 of operational funds to the U.S. Treasury.Paul said the U.S. Senators are appropriated $3 million a year for their office budgets and he’s been able to save nearly 15 percent of his annual costs. He hopes to set an example with his frugality, he said.“We look at all of our office expenses. We look at the coffee pot to the computers bought and we try to buy things as if it were our money we were spending, or your money that we were spending, and our goal is not to spend all of it, our goal is to save some of it," Paul said.If Congress offered incentives for lawmakers and staff to cut budgets, Paul estimates the U.S. could save $130 million annually, he said.Paul will continue finding cost savings but the amount may decrease each year as staff members earn raises, he said.“We’ve done a lot of things that I have not necessarily won the battle for. This is the one thing I have control over and that’s my office budget and I wanted to show the people of Kentucky that I have been frugal with their money and that I wanted to bring it back. And I’m very happy to have these taxpayers here to receive some of their own money back," he said.Over his six year term he could give back over $1 million, he said.