The federal government resorted to a favorite accounting maneuver Tuesday to stay under its debt limit, suspending the issuance of securities in a retirement savings program for federal and postal employees.

The Treasury Department announced the maneuver involving the Thrift Savings Plan’s government securities fund to keep the government below the $15.2 trillion debt ceiling, pending approval of a higher limit.

The fund, commonly called the G fund, consists of special-issue securities available only through the TSP. It operates much like a mutual fund for employees saving through the 401(k)-style program.

By not issuing new securities for the fund, the Treasury in effect frees up money on investment in the fund to stay below the debt limit. However, the G fund money remains on account with the Treasury, and investors “are guaranteed interest when Treasury securities are issued to the fund and they are guaranteed interest when securities are not issued to the fund,” TSP spokesman Tom Trabucco said.

A statement from TSP Executive Director Greg T. Long posted at said that the guarantee “has effectively protected G fund investors many times over the past 25 years. That protection, which was established by the Thrift Savings Plan Investment Act of 1987, will again work to ensure that G fund investors are completely unaffected by the limitation on securities issued by the U.S. Treasury. G fund account balances will continue to accrue earnings and be updated each business day, and loans and withdrawals will be unaffected.”

Trabucco said that the 1987 legislation “was enacted to protect investors in just this situation and keep them insulated from the politics of the debt limit.”

The Treasury has resorted to similar maneuvers about a dozen times during the TSP’s two-decade existence with no effect on investors, he said. The most recent occurrence was last spring and summer, when Congress and the White House deadlocked over raising the debt ceiling. Ultimately an agreement was reached last August.

As of the end of 2011, the G fund held about $148 billion of the roughly $295 billion on investment in the TSP. The TSP is open to military personnel and retirees as well as to federal and postal employees and retirees.