Contract notice deadlines: how to calculate them correctly

The notice deadline is the date that decides whether you get out of an agreement or are tied in for another term. Yet it's often worked out in someone's head, in an old spreadsheet, or not at all. This article explains how to find the deadline, the most common traps, and how to protect yourself against missing it by a single day.

This is general guidance, not legal advice. The terms of your specific agreement always take precedence.

The basic formula: expiry date minus notice period

Most business agreements have three pieces of information that belong together:

• Expiry date – when the current term ends.
• Notice period – how long before expiry you must give notice, such as 30 days or three months.
• Renewal – what happens if you don't give notice, often an automatic extension of one year.

The last day to give notice is the expiry date minus the notice period. It sounds simple, but the mistakes are in the details.

Days or calendar months?

The first thing to check is how the notice period is expressed.

Notice period in days

If the contract says “90 days' notice”, subtract 90 days from the expiry date. With an expiry date of 31.12.2026, the deadline is 02.10.2026. Note that this is not the same as three months.

Notice period in calendar months

If it says “three months' notice”, go back three months to the same date. If the agreement expires on 31.03.2027, the deadline is 31.12.2026. But what if that date doesn't exist in the month you land in?

The usual principle is to use the last day of that month:

• 31.12.2026 − 3 months = 30.09.2026 (September only has 30 days)
• 31.05.2027 − 3 months = 28.02.2027
• 31.05.2028 − 3 months = 29.02.2028 (2028 is a leap year)

This is exactly where many spreadsheets and rules of thumb go wrong. A spreadsheet that adds or subtracts 30 days per month will give the wrong answer several times a year.

Read the wording carefully

Some agreements have their own rules that change the calculation:

• “From the end of the month” – the notice period only starts at the end of the month in which notice is given. Give three months' notice on 10 September, and the agreement can end no earlier than 31 December.
• “Notice must be received” – it's not enough to send it on the deadline; the vendor must have received it.
• Quarter or year end – some agreements can only be terminated with effect from the end of a quarter or year.
• Minimum term – during a lock-in period you may not be able to give notice at all before a certain date.

When the agreement says something other than the standard formula, the agreement wins.

When the deadline falls on a weekend or public holiday

What if the last day to give notice is a Saturday, Sunday or public holiday? Whether the deadline moves depends on the agreement and the circumstances, and it's not something you should rely on.

The safe advice is simple: send your notice on the last working day before the deadline. Better still, build in a buffer of a few working days, so you have time if the person who needs to sign is off sick or the vendor's customer portal is down.

A practical approach is to keep two dates apart:

1. Final deadline – the contractual deadline.
2. Recommended send-by date – the final deadline minus, say, five working days.

The second date is the one to work towards.

Business contracts aren't consumer contracts

Many people are used to rules that protect them as consumers, such as subscriptions having to be easy to cancel. Consumer protection rules generally don't apply in the same way between two businesses. In business-to-business agreements, the parties are much freer to agree long minimum terms, long notice periods and automatic renewal.

That means you can't count on the vendor reminding you, or on a late notice being accepted. The deadline is your responsibility.

Checklist: finding the right deadline

1. Find the agreement. Read the contract itself and the general terms it refers to – not just the quote or the invoice.
2. Find the expiry date of the current term. If the agreement has already renewed once or more, count from the latest term.
3. Note the notice period and its unit. Days or months? Calendar months or “from the end of the month”?
4. Calculate the deadline and write down the calculation, for example “31.12.2026 − 3 months = 30.09.2026”.
5. Check the weekday. If the deadline falls on a weekend or holiday, move the send date to the working day before.
6. Add a buffer. Set a recommended send-by date a few working days earlier.
7. Share the deadline with at least one other person. A single calendar reminder for a single person is fragile.
8. Follow up the confirmation. Ask the vendor to confirm the termination in writing, and keep it.

How to send the notice

Check whether the agreement requires a particular form – for example, written notice to a specific e-mail address, or a form in the customer portal. Whatever the agreement says, it's wise to be able to document when the notice was sent and received. A short e-mail with a clear subject line, the contract number and an unambiguous sentence saying the agreement is terminated is often enough. Ask for a confirmation stating the end date.

In short

The notice deadline is the expiry date minus the notice period, but calendar months, month ends, leap years and bespoke terms make it easy to get wrong. Write down the calculation, send well before weekends and holidays, and make sure more than one person knows about the deadline.

If you'd rather not do the maths yourself, try our free notice period calculator. And if you have many agreements to keep track of, that's exactly what Licens is for: deadlines are calculated with the working shown, you're warned about weekends and holidays, and reminders go to more than one person.