Sears Roebuck & Co. will have to pay $5.5 million in dumping duty assessments within the next 30 days for Japanese-built television sets it imported from 1971 and 1973.

Sears Senior Vice President Jack F. Kincannon notified securities analysts yesterday that the Treasury had informed the retailer of the assessments.

Earlier this year, the Treasury announced that it found that Japanese television sets were sold below fair value in the U.S. between 1971 and 1973, and said in September that it would seek to collect $46 million in dumping levies from importers such as Sears who brought the sets into the country.

[Treasury officials said yesterday they could not confirm that Sears would have to pay $5.5 million in dumping levies.]

[Other major retailers also are going to be hit by the Treasury.]

[Dumping levies are assed against importers.]

Kincannon said the Treasury has deferred collections of these assessments pending its study of the appropriateness of making assessments on the masis of a fomula embodied in the Japanese commodity tax.

He said the Treasury Department has indicated in recent announcements that it will begin to compute dumping duty assessment on TV setsimported from Japan after 1973. "We don't know what the bill for the assessment will be, but in any event we will make payment under protest and will seek recovery of any amount possible," Kincannon said.