Business debt collection: how to calculate default interest correctly from July 2026

The focus: how to calculate default interest correctly from July 2026. What matters for creditors is which change directly affects deadlines, interest or evidence obligations, and by when it has to be reflected in their own systems.

The German base rate is adjusted on 1 January and 1 July and published by the Deutsche Bundesbank. Default interest builds on it with a margin of five percentage points against consumers and nine percentage points where no consumer is involved. Companies with a steady volume of receivables benefit from a fixed handover cycle rather than one-off ad hoc instructions. That keeps the case understandable for colleagues with no prior knowledge of it.

The change is felt most where many invoices with small amounts arise or where payment terms are long. For accounts receivable this means reviewing templates, interest calculation and reminder texts, regardless of company size.

Self-employed professionals and small businesses are included too, even though they rarely have a dedicated receivables function. A simple but consistently applied routine is especially valuable here. In business-to-business trade, nine percentage points above the base rate plus the EUR 40 flat fee are the usual ancillary claims. In concrete terms this comes back to one point: how to calculate default interest correctly 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.

The negotiating position shifts as well. Higher ancillary claims increase pressure to pay but make a transparent breakdown of the total amount even more important. The larger the volume, the more important standardised data formats and clearly defined service levels become. This care costs minutes and saves days if the matter is ever disputed.

The approach follows the calendar rather than instinct. Day one after the due date: check incoming payments. Days three to five: friendly reminder. Days ten to fourteen: formal reminder with a final period. After that period: decide on escalation. What is prepared properly at this stage shortens every subsequent step.

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. For business customers, a credit check before granting new payment terms is worth the effort. The thematic core stays the same: how to calculate default interest correctly 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. Framework agreements should state how partial performance and interim invoices are handled. In practice, reliability pays off faster than pressure.