September 4, 1981

As he looks toward the likelihood of another four years of running City Hall, Mayor Koch faces the prospect that his tasks will be shaped by circumstances that appear quite different, and less favorable, than what they seemed only a few months ago. The economy, he acknowledged the other day, is stagnant and the bond market for now seems inhospitable. The future for Federal and state aid is uncertain. Next year may bring a new Governor in New York and, even though Mr. Koch downplays the significance, new people as well in important positions in his own administration.

The Reagan Administration has devised a proposal that would require state agencies to assess most of the personal property and household effects of welfare recipients. Federal officials said today that the proposed rules would reduce cheating by insuring that the assets of welfare families did not exceed the new statutory limit of $1,000 per household. The rules are being reviewed by the Secretary of Health and Human Services, Richard S. Schweiker, and will take effect Oct. 1 if he approves them, as several of his top aides have recommended. Limit Set at $1,000 The Omnibus Budget Reconciliation Act of 1981, signed by President Reagan on Aug. 13, set a statutory limit for the first time on the assets that a family could have if it wanted to receive welfare under the program of Aid to Families with Dependent Children. The limit is $1,000, not counting the family's equity in a home and one automobile. Until the new law, regulations had set the limit at $2,000.

Decoys are indigenous to America; they are also examples of folk art. You may see them in the water and on the beach, in living rooms in Connecticut and in little shops on Third Avenue. If you want to see the best of the genuine article, however, visit the Museum of American Folk Art today. There are 70 decoys, not only for ducks, but for Canadian geese, mergansers, plovers and curlews, from New England, the Illinois River, the Delaware River, Chesapeake Bay and Long Island. Most of them are of wood, carved with simple tools in economical technique, but a few are made of canvas, leather or papier-mache, and they can be seen until Nov. 8. When you tire of decoys, look at the other exhibits in the museum, at 49 West 53d Street, which specializes in all kinds of folk art from Colonial times to the present. It is open today 10:30 A.M. to 5:30 P.M. Admission is $1; for the elderly and students, 50 cents. For information, call 581-2474.

LABOR will have its first parade in New York in 13 years Monday morning, with marching plumbers shouldering their plungers like drill rifles, with pr inters in regulation apron-and -folded-paper-hat uniform, with dozens of floats, 150 bands and members of the several performing unions of the A.F.L.-C.I.O. singin g, dancing and acting their way up Fifth Avenue from 26th to 52d St reet. The Labor Day weekend has over the years been the time for the last weekend in the country, for fairs, art shows and outdoor concerts. And, to be sure, the traditional leisure observances will again be with us -the Washington Square Outdoor Art Exhibit, the Richmond County Fair, entertainments at the South Street Seaport, the Bronx Botanical Garden and Forest Park in Queens. But this year also marks something of a return to the day's original intentions as a celebration of American labor.

Thrift institutions, acceding to the I.R.S., modified the bonus packages they are offering to promote the new tax-exempt savings certificates. They will continue to offer high-interest accounts as an incentive to purchase the certificates, but they will protect the tax-exempt status of the interest on the certificates by making their purchase optional. (Page A1.) The I.R.S. formally withdrew tax exemptions for any certificates bought as a requirement of the bonus plans rather than as voluntary purchases. (D4.) The one-year Treasury bills that will determine the yield on the new savings certificates were sold at a record rate of 15.056 percent on a discounted basis, for a yield of 18.01 percent. This would initally produce a yield on the certificates of 12.61 percent. Treasury bond prices fell sharply, producing yields approaching 15 percent. (D5.)