The Internal Revenue Service falsely placed a tax lien on President and Nancy Reagan this year because of a trainee's miscue in Texas, the IRS said yesterday.

Although the error was caught and corrected, the phony lien remains a permanent entry in the agency's computer files, a spokesman added.

As reported by the Kiplinger Tax Letter, an IRS official was demonstrating the agency's electronic lien system during a summer training session in Austin, and used the president's name as an example despite an IRS policy that real names, especially those of VIPs, not be used.

The demonstration caused no problems. But after the class, a trainee, practicing what she had been shown, hit the wrong buttons on her computer and thereby recorded a tax lien against the president at the Travis County courthouse.

IRS spokesman Rod Young confirmed the episode and said the agency has taken steps to see there is no recurrence. Young pointed out that the "Ronald Reagan" computer entry had been accompanied by a bogus Social Security number and a fictitious address, so the lien "wouldn't have had any effect anyway." While "we took steps immediately to make sure it was rescinded," Young said, "it is true that the 'lien' becomes part of a permanent record."

According to Ellen Murphy, IRS Public Affairs Director: "Pure and simple, this was a mistake made by someone who never had any intention of creating any sort of difficulty."