Borrowing against your nest egg is becoming as easy as stopping at an ATM.A growing number of companies now offer employees the option of being issued a debit card that taps a 401(k) loan. The card, called ReservePlus, allows workers to withdraw funds from their 401(k)s. The immediate concern for consumers is that impulse spending desires could trump their long-term savings needs. Here's how it works: After a company adopts the program, employees can transfer their approved loan line into a ReservePlus account online. Later, they receive a debit card that they can use to take out as much or as little as they need of the loan amount -- on average taking out 35% less than they applied for, says David Young, director of Reserve Solutions at The Reserve, the company offering the cards. The loan begins only after the money is removed from the account. Instead of a payroll deduction, participants are billed directly, and then pay back the loan through the same mechanisms used to repay a credit card. Depending on the employer, some may also qualify for a revolving loan -- taking out and paying back money as they need it. The ReservePlus loan program is growing. The card was first offered in 2003, and Young says employees who have used the debit cards for loans now number in the thousands. "There's a lot of interest in what we're doing," says Young. "It's a unique and logical solution to an archaic process."