The 36-year-old actor was on Australia's "Kyle and Jackie O" radio show recently when he was asked why his actress wife doesn't share his moniker.
"I think that she wanted to, I think she still may," he explained. "I think it was when we were coming back from America. We were living in Europe and deciding where to go. It was a complication of passports and so on."
But that's not to say Elsa won't change her surname in the future, as Chris added, "She might still do it."
The couple is now based in Australia with their three children, India, seven, and six-year-old Tristan and Sasha, with the "Thor" star recently opening up about how hard he is finding home schooling the trio during the coronavirus lockdown.