Your authority Debretts is clear that black tie is evening wear.
BLACK TIE
Black tie dress code, which is less formal than white tie, is the most frequently encountered formal evening wear, worn for dinners (both public and private), parties and balls, as well as some Season events such as Glyndebourne. It may also be described as 'dinner jackets', 'DJs', 'dress for dinner' or, in America, as 'tuxedos'. A host may also say 'we are going to change for dinner', which will traditionally indicate black tie. It should be described as a dinner jacket, not a dinner suit.
Black Tie: Men
- A black wool (barathea) or ultrafine herringbone dinner jacket, single-breasted or double-breasted with no vents, silk peaked lapels (or a shawl collar) and covered buttons. White dinner jackets were traditionally worn in hot climates but not usually in Britain, even in the summer.
- Trousers are black with a natural taper, and a single row of braid down each outside leg.
- A white evening shirt, with a marcella collar, bib and double cuffs, with a turn-down collar (not a wing-collar), worn with cufflinks and studs. A plain silk shirt with buttons may be worn but any kind of ruffles or frills should be avoided. Alternatively, a fly-fronted shirt, where the buttons are concealed, is acceptable. Adults should avoid novelty shirts and ties.