One Month's Notice Is Not Thirty Days' Notice

Notice clauses are among the shortest provisions in a contract and among the most litigated, because getting the date wrong can invalidate the notice entirely.

General information, not legal advice. What notice is required, and how it must be counted and delivered, is set by your contract and by local law.

Months, weeks and days are three different things

The notice period calculator accepts any mix of months, weeks and days because contracts use all three, and they do not convert into one another cleanly.

Serve notice on 31 January and the effective dates diverge immediately: one month gives 28 February, a span of 28 days; thirty days gives 2 March; four weeks gives 28 February again, though only by coincidence of that particular month.

Why the wording matters more than the number

“One month” and “30 days” look interchangeable and are not. In a month with 28 days, one month is shorter. In a month with 31, it is longer. If the contract says months, count months; if it says days, count days; and do not substitute one for the other because it seems close enough.

The same applies to “a month’s notice” versus “notice expiring at the end of a month”, which is a different requirement entirely and common in tenancy and employment contexts.

Inclusive or exclusive counting

A distinction the arithmetic cannot resolve for you: whether the day notice is served counts as day one, or whether the count begins the following day. Contracts and statutes differ, and a one-day error is enough to make a notice ineffective.

The calculator counts from the service date forward. If your rule counts differently, adjust by a day — and if you cannot tell which rule applies, that is a question worth asking before serving rather than after.

Service is separate from timing

A notice served correctly but late fails, and so does a notice served on time but incorrectly. Most contracts specify how notice must be given — in writing, to a named address, sometimes by a particular method — and some deem notice received a set number of days after posting regardless of when it actually arrived.

Where a deeming provision exists, it usually moves the effective service date later than the date you posted, which shortens the notice you have given. Read the deeming clause before working out the date, not after.

Build in a margin

Because inclusive counting, deemed service and delivery delays all push in the same direction, the safe practice is to serve earlier than the minimum. A few days of margin costs nothing and absorbs every one of these ambiguities at once.

Serving on the last possible day means every one of them has to fall your way.

Keep proof

Whatever method the contract requires, keep evidence of it: a copy of what was sent, the date, the address, and proof of despatch or delivery. Disputes about notice are usually disputes about whether and when it was received.

A correctly calculated date is worth nothing if you cannot show the notice went out on it.