Year-end, and the board asks: what exactly did the company do in marketing over the last twelve months, and why in that order? The answer is a string of decisions made on the fly — a campaign in March because there was suddenly time, flyers before a trade show because someone remembered at the last minute. The budget got spent, but nobody can show it in a form the procurement department recognises.
An annual marketing plan solves this before it happens. It lays out twelve months in advance — what happens, when, and within what budget range — so marketing decisions are made once, at the start of the year, instead of over and over again.