Beginning Aug. 1, newly-hired or rehired federal employees will be automatically enrolled in the Thrift Savings Plan.

Automatically-enrolled participants will have 3 percent of their salaries invested in the G Fund — which is backed by government securities and never decreases in value — unless they opt out within 90 days, according to a regulation published Tuesday in the Federal Register by the Federal Retirement Thrift Investment Board.

Participants who opt out will have their investments refunded to them, and will forfeit their agency's matching contributions. The board said it will soon require notarized signatures for refunds and all other withdrawal requests to protect participants against fraudulent withdrawals.

Employees who are rehired into the government after a separation of at least 31 calendar days will be automatically enrolled.

Automatic enrollees can elect to change the amount of money allocated to the TSP, and which funds they invest in.

The board has advised agencies to send newly-hired or rehired employees notices about the TSP, automatic enrollment and their options, and has sent agencies a sample letter they can use as a template.