Automate Dunning – Cut DSO by 21 days
Automated dunning for Lexoffice, DATEV or sevDesk: § 286/288 BGB compliant, with approval gates. Demo, figures modelled.
- Industry
- Finance / B2B / Agency
- Build, estimated
- 4–6 weeks
At a glance
- It starts with
- Daily Run
- The machine handles
- 11 of 13 steps
- A person keeps
- 2nd Dunning + Fee · Final Notice
- Bottom line
- -21 daysDSO Reduction
The problem
Writing dunning letters is the most uncomfortable task in any finance role. Nobody as a kid said "when I grow up, I'll send overdue notices."
But this exact task decides whether your working capital is healthy. With 30-day terms and 10-day late dunning, that's 40 days of credit you give your customer — for free.
In most SMBs it happens too late, too unstructured, too friendly-vague. Because nobody enjoys it and everyone hopes the customer just pays.
They don't. The machine does this — structured, friendly, on time.
Overdue receivables are the silent liquidity killer in mid-market finance. A typical German B2B firm with 200-600 open invoices spends 4-6 hours every Friday pulling AR aging reports, drafting dunning letters in Word, calculating late fees and § 288 BGB interest, and documenting sends. Results are inconsistent: long-standing customers get forgotten or treated too harshly, new customers slip through, and average Days Sales Outstanding (DSO) sits at 45-60 days instead of the target 30. Soft costs compound: customers are surprised by dunning letters because first contact often comes 21+ days after due date. Legal exposure grows when § 286 BGB notice timelines aren't cleanly documented. Every collections handoff costs 15-25% of the receivable plus interest – money that earlier, more consistent outreach would usually have saved. Extrapolated: a company with €2M annual revenue and 50-day DSO ties up ~€275,000 more working capital than at DSO 30.
The process, step by step
Scroll through. The diagram stays put and highlights the step you are on.
- 01
Daily Run
06:00 Cron
Daily dunning run starts at 06:00 as a cron job – before team start so approval requests are ready at the beginning of the workday.
- 02
Fetch Open AR
Lexoffice / DATEV / sevDesk
All open AR is pulled via Lexoffice, DATEV, or sevDesk API: invoice number, due date, amount, customer, prior dunning history.
- 03
Payment Reconciliation
Bank API / AR sync
In parallel, current payments are checked via bank API or invoicing system. Already-paid invoices exit the process immediately.
- 04
Customer Segmentation
Long-standing / New
Each remaining open item is mapped to its customer profile – long-standing, new, enterprise, public sector – which drives tone and deadlines.
- 05Branch
Which stage?
Gateway: based on days past due and customer profile, the next dunning stage is calculated.
- 06
Friendly Reminder
Day 3 – soft tone
From day 3 past due: friendly payment reminder without late fee. Tone: polite, service-oriented, assumes oversight.
- 07
1st Dunning
Day 14 – new deadline
From day 14: 1st dunning with new payment deadline (typically 7 days), still without late fee. Includes installment self-service link.
- 08Human decides
2nd Dunning + Fee
Day 28 + approval · § 288 BGB
From day 28 with human approval: 2nd dunning with late fee (typically €5-10) and statutory interest per § 288 BGB. Finance receives a Slack or email notification with preview and one-click approve. Tone: factual, formal.
- 09Human decides
Final Notice
Day 42 + approval · collections
From day 42 with management approval: final notice with concrete collections warning and 10-day ultimatum. Four-eyes principle for high amounts.
- 10
AI Personalization
Tone + context
Claude or GPT-4 personalizes the dunning text: industry, invoice context, payment history. Brand tone preserved, mandatory legal text unchanged.
- 11
Send + Delivery Receipt
Brevo / SMTP
Delivery via Brevo, Mailjet, or own SMTP – including delivery receipt and open tracking. PDF of the dunning notice generated and archived.
- 12
Audit Trail
GoBD 10 years
Every step – stage, timing, recipient, approver – is archived GoBD-compliant for 10 years. Full legal defensibility in later disputes.
- 13
Payment Received
Process closed
As soon as payment is detected, the system closes the dunning process automatically and notifies the customer with a brief confirmation email.
What changes
Possible setup, not a packaged product
The figures are modelled target values for a possible setup, derived from industry benchmarks and our own tests. They do not come from a customer project; real values depend on your business. We do not sell this setup as a finished product: we measure where your bottleneck is, then build with your team. For systems that require certification (e.g. HIS, gematik, DATEV-certified) we work with specialised partners.
Before vs. After
| Aspect | Before | After |
|---|---|---|
| Days Sales Outstanding (DSO) | Before: ~50 days | After: ~30 days (-21 days) |
| First customer contact after due | Before: 21+ days, inconsistent | After: Day 3 automated, friendly |
| Collections handoffs per year | Before: ~40 cases × 20% fee | After: ~10 cases (-70%) |
| Finance time on dunning | Before: 4-6h every Friday | After: ~30min approvals per week |
| Late fee calculation | Before: Manual in Word, error-prone | After: § 288 BGB day-accurate |
| Audit trail under dispute | Before: Patchy, Excel lists | After: GoBD-compliant, 10-year archive |
Technology
Technology Stack
Integrations
Systems this setup can connect to
- LexofficeInvoicing System
- Native Office API for AR, dunning stages, and payment reconciliation
- DATEV Unternehmen OnlineInvoicing System
- DATEVconnect integration for tax consultancies and mid-market on DATEV
- sevDesk / BillomatInvoicing System
- Alternative invoicing connection for SMB and freelancer portfolios
- Stripe Billing / GoCardlessInstallments
- Self-service installments via payment link, automated SEPA mandates
- Brevo / MailjetEmail Delivery
- Transactional email with delivery receipts, open and click tracking
- Slack / Microsoft TeamsApproval Workflow
- Approval notifications with one-click approve for finance and management
Security & Compliance
What the setup takes care of
- GoBD-Compliant Archive
- Every dunning event archived immutably for 10 years with timestamp, recipient, text, approver. BMF Nov 2019 compliant.
- GDPR & EU Hosting
- Processing exclusively in EU data centers (Frankfurt, Munich). Art. 28 DPA, automated retention and access request processes.
- § 286/288 BGB Compliance
- Default onset, late fees, and interest calculated audit-safe and day-accurate. Notice timing defensible in court.
- Encrypted Communication
- All dunning emails sent via TLS 1.3. DKIM, SPF, and DMARC configured to prevent phishing confusion.
Frequently Asked Questions
What would this look like at your company?
This workflow is a demo. Whether it pays off for you depends on where things get stuck at your company. The method page shows how to find out. To place a workflow of your own, use the free assessment. No call needed.
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