The Internal Revenue Service plans to auction off some $350,000 worth of Columbia Catering's perishable food delicacies at 11 this morning -- including 2,000 of Secretary of State George Shultz's favorite chocolate lace cookies, originally slated for a posh private dinner he gave Friday night in the James Madison Dining Room at State.

William Seltzer, president of Columbia Catering, said last night he had not been told of the auction. "You'd think they'd make a public notice. I might want to buy some of it myself."

Money from the auction of the fancy foodstuffs from Columbia Catering's freezers and refrigerators in Rockville will go toward paying the two 1984 liens totaling $240,007.70 that the IRS claims Columbia owes, according to IRS Baltimore spokesman Domenic Laponzina.

"If the liability is paid before 11 a.m. tomorrow, the property will be returned. The money represents employe withholding tax, interest and penalties," Laponzina said.

Seltzer emphatically denies the amount due the IRS. He says he paid the $118,656.49 due for the first half of 1984, and owes $121,351.21, including penalty and interest, for the second half.

Seltzer's lawyer, Paul Schleifman of Grossman and Flask, who learned about the proposed sale from a newspaper reporter, said late yesterday, "We may be forced to file for bankruptcy before the auction to protect my client's interests. How can my client fulfil his obligations if he does get back in his building? The IRS code requires them to give notice of the sale of the perishable goods and inform the owner of the appraised value. We haven't received either required notice."

An IRS agent padlocked Columbia Catering Thursday at 4 p.m., leaving the chocolate cookies, several other kinds of cookies, "boxes of strawberries, as high as your head, fancy meats, vegetables and desserts inside," said Seltzer.

Seltzer said the agent told him she was closing down the business Thursday because she wanted to take Friday off.

"The taxpayer had signed a consent that action could take place anytime within 10 days," Laponzina said.

Seltzer said he had already contracted to do "$250,000 worth of State Department Diplomatic Reception Room functions, including the Friday dinner and a Saturday lunch for Secretary Shultz, a wedding, two bar mitzvahs and 12 other parties including one at the Pension Building and another at the Departmental Auditorium. Some of those events are once-in-a-lifetime for the people. They're depending on me to make them go just right. I just hate letting them down."

For some events, including the weekend State functions, Seltzer turned the jobs over to Ridgewell's, which may be the nation's largest caterer with 180 full-time employes. "But I came along to watch over the parties to be sure everything went right. I knew just how the clients wanted them done. I and some of my staff worked for nothing. But we couldn't leave people's important parties in the hands of total strangers."

Jim Caulfield, Ridgewell's executive vice president, said, "We told him we didn't want to pick over anybody. We said we'd help him do 16 functions, at his prices. We were glad to help him and his customers. We hope he can get out of this problem. Competition is good for us." Caulfield said he wouldn't bid at Seltzer's auction. "I don't think that would be fair."

Seltzer started his business 15 years ago with one truck and a few employes. Since then the company has boomed, with 40 staff employes and 200 waiters on call. Seltzer, who does "99 percent" of the formal, elegant entertainment on the State Department's exquisitely remodeled penthouse floor, is well known for his lavish food. Cocktail buffets cost about $30 per person, and that includes cloth napkins; seated, multicourse dinners, often with historical recipes and centerpiece pheasants still with feathers, go up from there. Food, wine and service cost $200 per guest at a recent six-course dinner for which donors to the State Department Fine Arts project each contributed $1,500.

Clement Conger, curator of the State Department Diplomatic Reception Rooms collection, said, "It's Bill Seltzer's personal touch that makes the difference. And his food is so good." Conger added that even with extra attention, it often takes at least a month for Seltzer to be paid by State.

Seltzer explained that his money problems came "from not having enough capital." He buys expensive food, top vintages of wine and champagne, pays to have it prepared and served and then has to wait to be paid by his clients. "They all pay up, but right now, for instance, I'm owed $100,000," he said.

Seltzer said his stockholders would meet last night.