Goodbye government green. Hello rainbows.

The familiar punch-card check that Uncle Sam has used for 40 years to pay his bills officially is on its way out, replaced by a lightweight paper check that can be folded or spindled but definitely not mutilated, said William E. Douglas, commissioner of financial management at the Treasury Department.

The first recipients of the new check will be residents of the District, Maryland, Delaware and Pennsylvania who are due a federal income tax refund. Eventually, up to 615 million will be used annually, but that number will drop in future years as the Treasury increasingly switches to electronic fund transfers to make payments. Currently about 25 percent of the government's bills are by wire transfer; by 1990, Treasury spokesman Charlotte Mehuron said, "we're shooting for 65 percent."

The new check's "rainbow" front, which also features a Statue of Liberty drawing, is designed with anti-counterfeiting features in hopes of foiling even sophisticated color copying machines. Mehuron said counterfeited checks cost the government $6.4 million a year.

The new checks also are expected to save the government $6 million a year because they will be printed on less expensive paper stock.