He was nominated for a 1974 Joseph Jefferson Award for Best Actor in a Principal Role for his performance in "The Play's The Thing", at the Goodman Theatre in Chicago, Illinois.
Children: Molly Tambor (b. 1975) and Gabriel Kasper (b. December 10th 2004).
Played multiple characters on "Three's Company" (1976).
He became a father and grandfather in December 2004. His wife Kasia gave birth to son Gabriel Kasper on December 10 and his daughter Molly Tambor gave birth to son Mason Jay Moore on December 14.
He originally played Tom Abernathy in Miss Congeniality 2: Armed and Fabulous (2005). However, when the scene needed to be re-shot, he was shooting "Arrested Development" (2003), so the scene was re-shot with Stephen Tobolowsky. The version of the scene with Jeffrey can be seen on the DVD.
His wife Kasia gave birth to their second child, a girl named Eve Julia, on December 10th 2006.
Sold his five-bedroom Cape Cod-style house in Los Angeles' Pacific Palisades neighborhood for $3.3 million. He had purchased the house in early 2005 for $2,749,000. 
He purchased a four-bed, five-bath, 3,591 sq ft home in Topanga, California in 2008 for $1.675 million.
His wife, Kasia, gave birth to their third and fourth children, twin sons Hugo Bernard and Eli Nicholas, on October 4, 2009. Tambor had revealed the pregnancy in June 2009.