Can you wear a cumberbund with tails?

A cumberbund is not worn with tails. A cumberbund is a waist sash typically worn with a tuxedo or formal dinner jacket. Tails or tailcoat refer to a formal coat with elongated tails at the back, traditionally worn for white-tie events. In formal attire, a waistcoat or vest is typically worn with tails, but not a cumberbund. A cumberbund is more commonly paired with a regular dinner jacket.