Invoice is not paid: how to calculate default interest from July 2026

The framework around dealing with unpaid invoices changes regularly, through new interest rates, revised format obligations or economic developments. What counts is not the announcement itself but the question of which master record, which template and which process step now needs adjusting.

The cut-off date matters: the rate applicable during the relevant period of default is the one that counts. Where default runs across a cut-off date, the calculation is split into sections. A brief confirmation of receipt from the customer saves a great deal of later discussion. Settling this point once removes the need to renegotiate it in every individual case later.

Practically every company that works with payment terms is affected, from trades businesses through retail and e-commerce to service providers and SaaS vendors. The difference lies less in the sector than in the volume and structure of receivables.

Business-to-business trade partly uses different values than dealings with consumers. Anyone serving both groups should hold two separate rule sets in the system. For recurring services, a consistent invoice structure prevents queries from arising in the first place. For the constellation set out here the rule is: how to calculate default interest from July 2026.

For day-to-day operations this mainly means rework on master data and templates. Interest calculation, reminder letters, instalment plans and every report built on open items and days in default are affected.

Anyone handing receivables to a service provider should supply the calculation basis with them. Otherwise reconciliation work arises that slows the whole process. When an invoice stays unpaid, proof of delivery and of the invoice content is the first point to be checked. Small improvements here work through the entire receivables portfolio.

A sequence with few, clearly timed stages works best. After the due date comes a short reminder, a few days later a formal reminder with a specific date, then the announcement of handover. Each stage is documented before the next begins. What counts is less the perfect solution than one that is actually applied day to day.

Every stage needs a date, a channel and an owner. Follow-up dates are stored in the system so that no deadline lapses and no case is left sitting. Unpaid invoices often have a formal cause: a missing purchase order number, the wrong recipient or an unclear description of services. The link to the subject of this article is direct: how to calculate default interest from July 2026.

Three areas remain worth watching: the semi-annual adjustment of the base rate, the trend in corporate and consumer insolvencies, and the further stages of the e-invoicing obligation. All three act directly on the receivables portfolio and on process design.

It also pays to look at your own customer portfolio. A cluster of late payments at individual customers is an early warning signal that appears before any statistic. The more precisely an invoice describes the service delivered, the harder it is to delay payment with follow-up questions. In practice, reliability pays off faster than pressure.