Black tie or lounge suit

[going]

Partners are allowed to dp's work party this year - the invite states Black tie or lounge suit.

Black tie would sugest a full length dress, but that would be over dressed for lounge suit!

Help!

imo it has to be one or the other. Not both.

Lounge suits for men in the evening would indicate "cocktail" for women.

TBH, these days many women wear knee length for black tie anyway.

Any more details on the event to help decipher the code?

No other dtails - DH said that the company's boss probably wants Black tie but HR know people will back out so have given a choice of lounge suit. Really confusing.

hmm......I would be tempted to go for a fabulously dressy knee length cocktail dress then. Covers both angles :)

Cocktail dress. I used to go to DH's work black tie parties and no-one wore full length dresses. AFAIK full length is only strictly necessary for white tie events these days - or proper charity 'Ball' events.