It could cost the Federal Communications Commission upwards of $1 million to pay back $163 million in license fees that have been declared illegal, and it will take a year to figure out how to do it and another year to get the job done, the FCC's staff said yesterday.

The commission ordered the staff to start planning how to pay back the money, even though it has yet to decide how much must be refunded.

FCC license fees for everything from citizen's band radios to television stations were declared illegal by federal courts in 1975 because they did not reflect the cost of licensing or the value of the licenses to those who get them.

Since the beginning of 1977, the commission has not been collecting license fees, but it has yet to return any of the money that the court said was collected illegally between 1970 and 1975.

The commission set those wheels in motion yesterday, under pressure from the U.S. Circuit Court of Appeals, which had given the FCC until Friday to get moving.

But the commission still has not agreed to a new fee schedule which meets the criteria set by the courts, and therefore doesn't know how much it must repay.

FCC staff members said they will start with a system for repaying fees of $20 or more; there are only 270,000 of those, totaling $87 million.