Automate Dunning – Cut DSO by 21 days
Cut DSO by 14-21 days with automated dunning for Lexoffice, DATEV, or sevDesk. 70% fewer collections cases, § 286/288 BGB compliant, approval gates.
- DSO Reduction
- -21 days
- Industry
- Finance / B2B / Agency
- Implementation
- 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.
How the process runs — 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.
Our Solution
An orchestrated dunning workflow that plugs natively into your existing invoicing system – Lexoffice API, DATEV Unternehmen Online, sevDesk, or Billomat – and runs a daily AR check. Four configurable stages (friendly reminder, 1st dunning with new deadline, 2nd dunning with late fee and interest, final notice with collections warning) with customer-segment-specific escalation profiles. Long-standing high-credit customers get gentler tone and longer deadlines; new customers strict. Payment reconciliation runs in real time before every stage – no customer gets dunned for an already-paid invoice. Messages are AI-personalized (industry, invoice context, payment history) while preserving brand tone, with human approval gates from the 2nd stage onwards. Legal-grade deadline math per § 286 BGB, 10-year GoBD-compliant archival, and full GDPR audit trail built in. Optional self-service installment flow lets customers propose payment plans via a link, auto-configured in Stripe or GoCardless. Outcome: DSO drops 14-21 days, collections handoffs drop 60-80%, finance team reclaims 3-5 hours per week.
- Native Invoicing Integration
- Direct integration with Lexoffice, DATEV Unternehmen Online, sevDesk, or Billomat – no dual entry, no CSV exports. AR is synced hourly.
- Customer-Specific Dunning Profiles
- Per segment (long-standing, new, enterprise, public sector): own escalation profiles with tone, deadlines, late fees, and path.
- Real-Time Payment Reconciliation
- Before each stage, the system checks current payments via bank API or invoicing system. Already-paid invoices drop out of the dunning queue automatically.
- § 286/288 BGB Auto-Calculated
- Default onset, late fees, and statutory interest (5%/9% above base rate) calculated day-accurate and audit-safe. Notice timing verifiable in court.
- Approval Gates from Stage 2
- Reminder and 1st dunning run fully automated. From 2nd dunning (with late fee) onwards and before collections: human approval via Slack, Teams, or email link.
- Installment Self-Service
- 1st dunning email includes a link for customers to propose installment plans themselves. Auto-configured via Stripe Billing or GoCardless SEPA mandates.
What comes out of it
Possible setup, not a packaged product
The figures shown are target values and expected magnitudes for a possible setup – based on industry benchmarks, public studies of comparable setups, and our own tests on a real stack. They are not measured outcomes from a specific customer project; actual results depend on company size, process maturity, and integration depth. We do not offer this setup as a packaged product. We help teams design, automate, and run such processes themselves – through architecture consulting, workshops, and implementation support with n8n. For regulated third-party systems with certification or license requirements (e.g. HIS, gematik, DATEV-certified), we partner with specialized providers.
- -21 days
- DSO Reduction
- ~€275k
- Working Capital Freed
- 3-5h
- Weekly Time Saved
- -70%
- Collections Handoffs
DSO from ~50 to ~30 days, 60-80% fewer collections cases, 3-5h/week reclaimed
Before vs. After
| Aspect | Before | After |
|---|---|---|
| Days Sales Outstanding (DSO) | ~50 days | ~30 days (-21 days) |
| First customer contact after due | 21+ days, inconsistent | Day 3 automated, friendly |
| Collections handoffs per year | ~40 cases × 20% fee | ~10 cases (-70%) |
| Finance time on dunning | 4-6h every Friday | ~30min approvals per week |
| Late fee calculation | Manual in Word, error-prone | § 288 BGB day-accurate |
| Audit trail under dispute | Patchy, Excel lists | GoBD-compliant, 10-year archive |
Technical facts
Technology Stack
Integrations
Seamless connection to your existing infrastructure
- 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
Enterprise-ready with highest security standards
- 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
Does this look like your setup?
If this workflow resembles yours, we will look at it together — and tell you honestly whether automating it pays off.
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