The federal government plans to begin automatically enrolling new employees in the Thrift Savings Plan in August, the board governing the plan said Tuesday.

Once in place, new employees will begin contributing 3 percent of their paychecks to the TSP's government securities-backed G Fund. Their agencies will match that 3 percent, and contribute another 1 percent on top of that.

New employees can opt out of TSP within 90 days and receive a full refund without suffering an early withdrawal penalty.

Military service members will not be automatically enrolled.

TSP participants also will gain a Roth option, most likely in January 2012. That option will allow participants to make taxable contributions to a retirement account and then make tax-free withdrawals in retirement. Under the current system, participants make tax-free investments and then pay taxes when they withdraw money.