Interest Note Poland: Template & Rates 2026

TL;DR - Key facts before you read on

A client didn't pay on time? Polish commercial law gives you the right to charge statutory interest - automatically, from the first day the invoice is overdue. Here's what you need to know:

• Legal basis: Act on Payment Terms in Commercial Transactions (Dz.U. 2013 poz. 403, as amended)
• 2026 statutory interest rate (B2B, private debtor): 15.75% per year
• Interest starts accruing: Day one after the payment deadline on your invoice
• An interest note is not a VAT invoice - it does not go through KSeF and has no prescribed legal format
• Claims expire: After 3 years - but the sooner you send the note, the better your recovery odds

What is an interest note (nota odsetkowa)?

An interest note - known in Polish as a nota odsetkowa - is a formal commercial document that a creditor sends to a debtor to demand payment of statutory interest on overdue invoices. It is separate from the original invoice and separate from a general payment demand letter.

Think of it this way: the invoice is the obligation, a payment reminder asks for the invoice to be paid, and the interest note says "here is how much you now owe on top of the original amount because you paid late."

It is important to understand what an interest note is not: it is not a VAT invoice. In Poland, VAT invoices for most VAT-registered businesses must go through KSeF (Poland's mandatory e-invoicing system, which becomes compulsory for all VAT payers from April 1, 2026). An interest note falls outside that system entirely. You issue it as a standard commercial document - a Word file, PDF, or generated from your collections software.

Interest note vs. payment demand letter - what's the difference?

Document	What it claims	When to use it
Interest note	The statutory interest accumulated on a late invoice	When you want to formally claim the interest amount
Payment demand letter	The full outstanding balance (principal + interest)	When you want to recover the entire overdue amount

In practice, you can - and often should - send both at the same time. The payment demand letter drives the main recovery effort; the interest note makes the exact interest figure clear and legally documented. Sending both signals that you are serious and have done the paperwork properly.

Legal basis: when do you have the right to charge interest?

Your right to statutory interest in B2B transactions is governed by the Act of March 8, 2013 on Payment Terms in Commercial Transactions. The law is creditor-friendly in several important ways:

• Interest accrues automatically from day one of the delay - you do not need to send any prior warning or notice for the right to crystallise
• You do not need to prove financial loss - the fact of late payment is sufficient
• The default maximum payment term in B2B is 60 days (30 days if not explicitly agreed otherwise)
• If a contract sets a longer term, it must be objectively justified - courts can override unfair terms that disadvantage the creditor
• The right to claim interest expires after 3 years (statute of limitations)

One important nuance: the right to interest exists from day one of the delay - but your debtor only has a formal, documented obligation to pay it once you issue and send the interest note. Issuing the note converts your automatic legal entitlement into an active, timestamped claim. This matters if the case ever reaches court.

Statutory interest rates in Poland - 2026

Interest rates for commercial transactions are set twice a year by the Polish Ministry of Finance. They are calculated as a fixed premium above the National Bank of Poland (NBP) reference rate. With the NBP reference rate at 5.75% as of early 2026, the applicable rates are:

Transaction type	Annual rate	Calculation
B2B commercial transactions - private debtor	15.75%	NBP 5.75% + 10 percentage points
B2B commercial transactions - public entity debtor	13.75%	NBP 5.75% + 8 percentage points
Civil (non-commercial) late payment interest	12.75%	NBP 5.75% + 7 percentage points

The vast majority of standard B2B transactions fall under the first row - 15.75% per year. The public entity rate applies when your debtor is a government body, public hospital, municipality, or other public institution.

Important: The NBP reference rate can change. Always verify the current rate at nbp.pl or in the relevant Ministry of Finance announcement before issuing any interest note. Using an outdated rate weakens your position if the note is disputed.

How to calculate statutory interest - formula and worked example

The calculation is straightforward. You need three numbers: the overdue amount, the number of days the payment is late, and the applicable annual interest rate.

The formula

Interest = Overdue amount × Annual interest rate × (Days overdue ÷ 365)

Step-by-step worked example

Suppose you issued an invoice for PLN 12,000 (approximately EUR 2,790) with a payment deadline of January 15, 2026. Your client still hasn't paid on February 28, 2026.

• Invoice amount: PLN 12,000
• Payment deadline: January 15, 2026
• Date of note: February 28, 2026
• Days overdue: 44 days (January 16 to February 28)
• Applicable rate: 15.75% per year (B2B, private debtor)

Calculation:

PLN 12,000 × 0.1575 × (44 ÷ 365) = PLN 12,000 × 0.1575 × 0.12055 = PLN 227.74

On top of your PLN 12,000 invoice, you can claim PLN 227.74 in statutory interest - documented on a single interest note.

Multiple overdue invoices on one note

If a client has several unpaid invoices, you do not need to issue a separate interest note for each one. Calculate the interest for each invoice individually (each will have a different overdue start date and possibly a different overdue amount), then combine them all on a single note with a total figure. This is cleaner, easier for the client to process, and gives you one clean document if the matter proceeds to court.

A quick note on rounding

Round to two decimal places. Polish commercial courts accept standard rounding. Do not over-engineer this calculation - accuracy matters, but PLN 227.74 versus PLN 227.75 will not affect the validity of your note.

What your interest note must include

Polish law does not prescribe a specific format for an interest note - unlike VAT invoices, which have strict KSeF-mandated fields. However, a legally robust interest note that will hold up if challenged should contain the following elements:

• Date of issue
• Creditor details - your company name, registered address, NIP (Polish tax identification number)
• Debtor details - your client's company name, registered address, NIP
• Document reference number - for your own bookkeeping and traceability
• Legal basis - cite Article 7 of the Act on Payment Terms in Commercial Transactions (Dz.U. 2013 poz. 403)
• Table of overdue invoices - for each invoice: invoice number, gross amount, payment deadline, actual payment date or note date, number of days overdue
• Interest rate applied - state the annual rate (e.g., 15.75% per year) and its legal basis
• Interest calculation per invoice - show the working, not just the result
• Total interest amount due
• Bank account number for payment
• Payment deadline for the interest - typically 7 to 14 days from the date of the note
• Signature and company stamp - optional but recommended, especially for larger amounts

Showing your working - the formula, the rate, the days counted - is important. A debtor who tries to dispute the note in court will have a harder time if every number is transparent and auditable.

The interest note template (DOCX + PDF) is coming soon. Bookmark this page and check back for the update.

How to send an interest note - practical guidance

Delivery method

An interest note does not need to be delivered by any specific method to be legally valid. That said, your ability to prove delivery matters enormously if the matter escalates:

• Email - sufficient for most situations. Keep the sent email and any read receipts. This is the standard method for routine interest notes.
• Registered post with acknowledgement of receipt (list polecony za potwierdzeniem odbioru) - essential if you anticipate court proceedings or the amount is significant. The signed receipt card becomes evidence of delivery.
• Email plus registered post - the safest approach for large balances. Email creates an immediate digital record; the registered letter creates a legal one.

When to send it

There is no legal deadline for issuing an interest note - your right to interest expires after three years, so you technically have time. In practice, the timing strategy matters:

• Immediately after the deadline passes - sends a clear message that you track payments closely and respond promptly. This is the most effective deterrent against repeat late payment.
• Alongside a payment demand letter - combining both documents in one communication reinforces the seriousness of the claim and gives the client everything they need to process payment in one go.
• Before initiating court proceedings or handing the matter to a collections agency - the note becomes a key piece of documentation in any formal process. Courts expect to see it.

The data supports acting early: clients who receive formal interest documentation within the first two weeks of a missed deadline are significantly more likely to pay voluntarily than those who receive it after 60 days.

Frequently asked questions

Do I need to issue an interest note to be entitled to interest?

No. Your right to statutory interest arises automatically on day one of the delay - the law does not require you to issue any document for the right to exist. However, issuing and sending an interest note formally notifies your client of the exact amount owed and creates a dated, written record of your claim. Without it, your client can argue they were unaware of the obligation. Always issue the note.

Can the debtor deduct the interest they pay as a business expense?

Yes - interest paid on a valid interest note is a tax-deductible business expense for the debtor (a koszt uzyskania przychodu). This is a useful point to raise in negotiations: paying the interest and expensing it is more commercially rational for your client than continued delay, which accrues more interest while damaging the business relationship. It removes a common objection.

What if my client refuses to pay the interest?

You have two main options. First, pursue it through the Polish court system - the simplified procedure (postępowanie uproszczone) handles claims up to PLN 20,000, and the electronic payment order system (e-Sąd) is cost-effective for smaller amounts. Second, you can involve a collections agency, which takes on the recovery effort on your behalf. In either case, your interest note - properly issued and demonstrably delivered - is a critical piece of evidence. Do not skip issuing it even if you think the debtor will pay.

Does an interest note go through KSeF?

No. KSeF (Poland's mandatory e-invoicing system) applies only to VAT invoices. An interest note is a commercial document, not a VAT invoice - it is not subject to KSeF requirements and is issued outside that system entirely. This applies regardless of whether you are already using KSeF for your regular invoicing.

What about interest if the original invoice was disputed?

If your client has raised a genuine, documented dispute about the invoice itself (not just refusing to pay), interest may not accrue during the active dispute period on the disputed amount. However, undisputed portions of the invoice continue to attract interest. If a client raises a dispute that appears tactical rather than genuine, note the date and continue documenting - courts look unfavourably on spurious disputes used to delay payment obligations.

Can I charge interest above the statutory rate?

Yes, if your contract specifies a higher rate. However, the rate cannot exceed the maximum interest rate allowed under the Polish Civil Code (currently four times the NBP lombard rate). In practice, most businesses use the statutory rate - it is well-recognised, easy to calculate, and carries legal weight without requiring a specific contractual clause.

How Terminovo automates interest calculation and payment reminders

Tracking overdue days across dozens of invoices, recalculating interest as the NBP rate changes, and manually preparing interest notes is exactly the kind of work your software should handle - not you.

Terminovo automates the entire process, from the moment an invoice goes unpaid to the point where you generate a fully populated interest note with one click. Here is how it works:

1. Import your invoices - enter them manually, or connect directly via KSeF integration so invoices appear automatically
2. The system detects late payment from day one - no manual checking needed
3. Automated reminders go to your client via email or SMS, on a schedule you configure - a professional tone that preserves the business relationship while prompting action
4. Interest is calculated continuously using the current statutory rate - the system keeps up with any NBP rate changes
5. Generate a fully formatted interest note in one click - all required fields pre-filled, calculation shown, ready to send

Most overdue invoices get resolved at the reminder stage, long before an interest note is even needed. Terminovo's automated reminders have a measurably higher response rate than manual emails - because they go out on time, every time, with a consistent and professional tone.

For the invoices that do reach the interest note stage, Terminovo ensures your documentation is accurate, timestamped, and complete - whether you send it directly from the platform or download it to send via registered post.

Summary: 5 things to remember about interest notes in Poland

1. Your right to interest is automatic - it starts from day one of the delay, no prior notice required under Polish commercial law
2. The 2026 rate is 15.75% per year for standard B2B transactions with a private-sector debtor
3. The calculation formula is simple: Amount × 15.75% × (Days overdue ÷ 365)
4. An interest note is a formal demand document - send it by email as a minimum, by registered post if the amount is significant or proceedings are likely
5. Automation removes the friction - Terminovo calculates interest, sends reminders, and generates interest notes so you spend zero time on manual tracking

Start recovering overdue payments - without the spreadsheets

Automated reminders, real-time interest tracking, and one-click interest note generation. Terminovo works from the first day a payment is late - so most issues get resolved before they become problems.

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