Thirty days is not a month: be careful with payment reminders

No, “thirty days” and “one month” are not legally the same. If the law or your own terms and conditions stipulate a period of “one month,” do not cover this with “30 days”: the average month is longer (approximately 30.4 days). If you calculate a day too short in a payment reminder or demand letter, that reminder may be invalid, and you may not be allowed to invoke the associated consequences (such as collection costs or a contractual penalty). Therefore, adopt terms exactly as the law or your contract describes them.

A month or 30 days? The short answer

When law or contract refers to “a month”, you do not calculate with 30 days but with an actual calendar month. A month counted from, for example, January 15 runs up to and including February 15, regardless of how many days that month has. Because most months are longer than 30 days, “30 days” structurally turns out to be shorter. For your own memory:

• “A month” = a full calendar month, on average about 30.4 days, and in practice almost always longer than 30 days.
• “30 days” = exactly thirty days, and therefore usually too short to cover a period of “a month”.
• “A week” = not just seven separate days; a week usually runs from Monday to Sunday.

Why a payment reminder requires careful legal attention

Any entrepreneur can draft a payment reminder. However, such a letter is legally less innocent than it seems. A reminder or demand letter is often the stepping stone to further steps: default, charging interest and collection costs, or invoking a contractual or statutory consequence. If the deadline stated in the letter is incorrect, the entire structure can fall apart.

Moreover, your reminder must not conflict with what you yourself agreed upon in your terms of purchase or delivery, and statutory provisions can limit your freedom. An incorrectly formulated deadline is then not a detail, but a substantive error. Nationale-Nederlanden Levensverzekering Maatschappij also experienced this.

The case: “thirty days” cost the insurer tens of thousands of euros

In this case, the insurer sent reminder letters because a client failed to pay his subsequent premium. In the final letter, the client was given a period of “thirty days” to make the payment. When that period expired, the insurer made the life insurance policy premium-free. The financial complaints institute Kifid had to assess whether the insurer was permitted to do so.

What went wrong?

Article 7:980 of the Dutch Civil Code imposes a so-called duty to warn on insurers. In the event of non-payment, the policyholder must be given a period of at least one month to make the payment. Only if that period expires unused may the insurer make the policy premium-free. This warning is a precondition: if it is not properly complied with, the insurer may not invoke the consequence.

The reminder letter, however, did not refer to “one month,” but to “thirty days.” Since this concerns a statutory minimum period affecting the validity of the warning, it had to be assessed whether one month equals thirty days. According to Kifid’s judgment, a month is on average longer than thirty days — assuming an average monthly length of approximately 30.4 days. The fact that the actual premium-free status was only established later was irrelevant: if the precondition had not been met, the insurer was not permitted to intervene.

A subtle difference with a significant consequence: the insurer had to reimburse the consumer a substantial amount. It shows that one wrong word within a deadline can undermine an entire sanction.

What this means for your reminders and notices

The lesson extends beyond insurance alone. For every reminder, demand for payment, or notice of default, you must formulate the time limit accurately and correctly. To do so, refer to both the applicable law and the clauses in your own general terms and conditions (including delivery terms).

The same applies to invoking your own terms and conditions. Do your terms and conditions refer to “one month”? That does not automatically equate to “thirty days”. Is a contractor required to deliver a document “next week”? Then “next week” is not simply seven days. Also, pay close attention to the difference between “up to” and “up to and including”: there is a whole day — and sometimes a whole case — in between.

Common mistakes in a payment reminder

• Rounding off the term to “30 days” while the law or your contract requires “a month”.
• Unclear start date: do not state from when the term runs (shipping or receiving date).
• “Until” versus “up to and including”: an ambiguous end date making the last day uncertain.
• Conflict with your own terms and conditions: citing a term or consequence that deviates from your general terms and conditions.
• No notice of default or a late notice before charging interest and collection costs.

How to formulate a legally watertight deadline

1. Adopt the term as the law or your contract literally describes it (“one month” remains “one month”).
2. Specify a concrete end date and indicate from which moment the term runs.
3. Use “up to and including” if you want to count the last day, and be consistent with that.
4. Check that the letter aligns with your general terms and conditions and with previous correspondence.
5. Keep proof of shipment so that you can prove later when the period began.

Not a standard letter from the internet, but custom-made

A legal document simply picked up from the internet is rarely tailored to your situation or your own terms and conditions. One wrong word — “thirty days” instead of “one month” — can, as this case shows, have far-reaching consequences. A correct reminder or notice of default that matches your contract will keep you safe and sound.

Frequently asked questions about payment reminders and installments

Is a month the same as 30 days?

Legally, usually not. Because most months are longer than thirty days, “30 days” does not automatically cover a statutory or contractual term of “one month.” If the law or your contract stipulates “one month,” include “one month” literally.

What happens if the time limit is too short in my memory?

In that case, the reminder may be invalid. If a correct deadline is a condition for a specific consequence — such as default, collection costs, or the invocation of a contractual sanction — then you may not be allowed to invoke that consequence until you have issued a correct reminder.

Do I need to send a reminder before I can charge collection costs?

In many cases, you must first formally put the debtor in default and grant them a reasonable period before default occurs and you can claim interest and collection costs. Furthermore, additional rules apply to consumers. Have the correct sequence and timeframe tailored to your situation and conditions.

What timeframe must I give a consumer in a formal demand letter?

For consumers, you must generally first send a final, free reminder with a payment deadline before you may charge extrajudicial collection costs. This period starts running from the moment the consumer receives the reminder. Formulate the deadline unambiguously and take into account the time it takes for the mail to enter, so that the consumer retains the full deadline.

What is the difference between a payment reminder, a demand letter, and a notice of default?

A payment reminder is a friendly reminder. A formal demand is more forceful and often links a final deadline and consequences to non-payment. A notice of default formally places the debtor in default and is usually required before you can invoke further rights. The correct term and timeframe depend on your contract and the law.

What exactly does “up to and including” mean in a term?

“Up to and including” includes the last day mentioned; “to” excludes that day. The difference of that one day can determine whether a deadline has been utilized on time. Therefore, be consistent and unambiguous in your wording.

Ensure your reminders and terms and conditions are legally sound?

Are you unsure whether your payment reminders, dunning letters, and general terms and conditions use the correct time limits? The legal experts at MKB Juristen review your documents and tailor them where necessary, so you don't stumble over a single word.

• Need help with unpaid invoices and the process from reminders to collection? Check out our page on debt collection.
• Questions about your contracts and terms and conditions? Read more about contract law or arrange your legal assistance.

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