With an evidentiary hearing looming, the Justice Department said the Swiss and U.S. governments had an “agreement in principle on major issues” to substantially resolve an Internal Revenue Service demand for the names of 52,000 U.S. citizens suspected of tax evasion on assets secretly held at the Swiss bank UBS.

Tax litigators speculated a deal would center on the identities of wealthy Americans who met with UBS bankers in the United States on income tax avoidance schemes based on assets in foreign shell companies or foundations. An agreement was expected to exclude other UBS customers who have accounts that have been passed through estates and foreign-born citizens who opened accounts before moving to the United States.