Friendship Savings & Loan has not decided whether to offer the new 6 month money market certificates that become available today. A story in Friday's Business & Finance section said that the firm had decided against offering the certificates.

Nearly three-quarters of 31 banks and savings institutions in metropolitan Washington plan to offer new 6-month money market certificates starting June 1, according to a Washington Post random survey.

The savings certificates, sold in minimum denominations of $10,000, will carry interest rates equal to the average yield of 6-month Treasury bills. Thrift institutions are allowed to pay 1/4 percent more than banks on these investment instruments. The latest average yield paid on 6-month Treasury bills was 7.14 percent; the current ceiling on 6-month time deposits for banks and federally-chartered thrift institutions is 5 1/2 and 5 3/4 percent, respectively.

A telephone survey showed 74 percent of the institutions polled plan to offer the certificates. Only two, Peoples Security Bank and Friendship Savings & Loan, both in Maryland, said they had decided against them. A fifth of the institutions contacted are undecided.

The new certificates, authorized recently by bank regulatory agencies, are designed to allow private financial institutions to compete more easily against the government and in the open market for dollars. During the first quarter of this year, net new deposits in savings institutions - which provide the bulk of home mortgage credit - declined 36 percent from the same period in 1977, according to Federal Home Loan Bank Board figures.

Total net savings flow into S&Ls last year was about $50 billion. Without the new, higher interest rate certificates, FHLBB chairman Robert H. McKinney has estimated that the 1978 inflow would fall to the low thirty billions. By adding the new instruments, the board expects deposits to increase about $6 billion, for a net of $40 billion.

Five years ago, when interest rates also were soaring, the savings industry experienced a situation called "disintermediation," where customers take out more money than they put in - shifting their funds to investments with higher yields.

At that time, the S&Ls responded with the so-called wild card certificate. For four months there was intense competition to sell 4-year, $1,000-and-up certificates of deposit for 7 1/2 percent, 8 percent and higher interest. Congress ended the race by imposing a 7 1/2 percent ceiling, except on deposits over $100,000.

As the current credit squeeze became apparent, the FHLBB, Federal Reserve Board and other agencies decided that potentially the greatest loss of revenues would come from medium large savers and investors. Hence the $10,000 minimum for the money market certificates. A new 8 percent certificate for 8 years for minimum deposits of $1,000 also has been authorized and many area banks or S&Ls surveyed plan to offer it, too.

The new instruments are most popular in California and Texas, where the demand for housing funds is strongest. The most negative reactions, according to FHLBB's Marshall Kaplan, have come from New York and New England. A spokeswoman for Friendship Savings & Loan in Chevy Chase said its directors were afraid the new certificate rates would make mortgage rates soar.

For the investor in a high income tax bracket, government officials said, Treasury bills may still be a better buy because they are not subject to state and local taxes, as are the certificates. Moreover, Treasury bills are negotiable, so the bearer can sell them before maturity to take advantage of rising rates. [LINE ILLEGIBLE] Other banks and brokers charge between $10 and $25 commission on a bill.

The following institutions among those surveyed plan to offer 6-month market certificates as of June 1:

District banks: American Security, National Savings and Trust, Union First. District savings and loan associations: Columbia Federal, First Federal of Washington, Home Federal, National Permanent, Perpetual, Washington Federal.

Maryland banks: Maryland National, University National, Union Trust. Maryland savings and loan associations: Community, Government Services, Metropolitan Federal.

Virginia banks: Dominion National, First American, First & Merchants, United Virginia, Virginia National. Virginia savings and loan associations: First Federal of Alexandria, Northern Virginia, Washington and Lee.

Undecided: Chevy Chase Savings and Loan, Citizens Banks and Trust, First National Bank of Maryland, National Bank of Washington, Riggs, Suburban Trust.