Board of Inland Revenue v Haddock is a fictitious legal case written by the humorist A. P. Herbert for Punch magazine as part of his series of Misleading Cases in the Common Law. It was first published in book form in More Misleading Cases in the Common Law. The case evolved into an urban legend.

Sir Alan Patrick Herbert CH, was an English humorist, novelist, playwright, law reformist, and, from 1935 to 1950, an independent Member of Parliament for Oxford University.