Multi-Mandant cockpit that ingests DATEV exports from N Lexoffice/sevDesk/Papierkram accounts → consolidated P&L dashboard, cross-entity invoicing (Holding ↔ operating UG), shared customer/supplier directory. €29/mo flat for up to 5 entities. Stops the 'pay 2-3× and switch accounts' tax.

What we ship

**Core features (MVP)**

• Single-pane-of-glass dashboard for 2-10 GmbHs/UGs/Einzelunternehmen — consolidated KPI (Umsatz, Cash, Gewinn, USt-Saldo) with per-Mandant drilldown
• Lexoffice / sevDesk OAuth + DATEV-CSV import fallback: each entity connects in 30 seconds, nightly sync via Celery
• Cross-entity DATEV export: single ZIP with N Buchungsstapel (one per Mandant) + master Konzern-Übersicht for the Steuerberater
• Cross-entity invoicing: Holding bills the operating UG, system automatically books the mirror entries in both Mandanten and flags §14 UStG required fields
• AI duplicate detection (Claude Sonnet) — catches double-booked transactions between Mandanten (classic Holding-Operativ cash-transfer pain)

**Primary user flow**

1. Onboarding: connect the first Mandant via Lexoffice OAuth (or DATEV-CSV upload) → cockpit shows the single-entity dashboard in 2 minutes

2. Add-second-Mandant flow: "+ Mandant hinzufügen" → choose source → consolidated dashboard auto-renders with side-by-side comparison and Konzern-Sum

3. Cross-entity invoicing wizard: "Holding rechnet operativer UG" → pick position templates → Stripe/SEPA payment + auto-booking on both sides + §14 UStG check

4. End of month: one click on "DATEV-Export für alle 5 Mandanten" → ZIP downloads with correctly segmented Buchungsstapel files + email to Steuerberater

**What it looks like**

• **Landing**: "Statt 5× Lexoffice für €145/Monat — €29/Monat für alle Mandanten". Hero is a split screen — left side 5 chaotic Lexoffice windows with account-switcher, right side a single cockpit dashboard with all 5 Mandanten side-by-side. ROI calculator: "Bei 3 Mandanten sparst du €43/Monat = €516/Jahr". Trust: "GoBD-ready", "EU-only data residency", "Lexoffice + sevDesk + DATEV partner". Testimonial quote from an r/selbststaendig Holding founder.
• **Main app**: top bar — Mandant tabs (Holding | UG-Ops-1 | UG-Ops-2 | + Add) + Konzern toggle. In Konzern mode the main area splits into 2/3 KPI grid (Umsatz/Cash/Gewinn/USt × Mandant columns with totals) + 1/3 right panel "Cross-entity Activities" (recent inter-company invoices, duplicate warnings, sync status per Mandant). Bottom: single-row consolidated Cashflow chart. Sidebar nav: Dashboard / Mandanten / Cross-entity Invoicing / DATEV-Export / Settings.
• **Output**: ZIP file `Konzern_DATEV_Export_2026-04.zip` containing sub-folders per Mandant (`Holding-GmbH/EXTF_Buchungsstapel.csv`, `UG-Ops-1/EXTF_Buchungsstapel.csv`, etc.) + a master `Konzern_Uebersicht.pdf` (consolidated P&L, inter-company eliminations, signed timestamp). Cross-entity invoicing output: paired PDF invoices with matching reference numbers (`HLD-2026-001` and `UG1-2026-EIN-001`).

**MVP build plan** — 14 days

Source signals

• **SIG-20260425-dach-micro-saas-utility-multi-company-blocker** — "Geht nicht mit einem Account" + comparison sites confirm as #1 switch reason (SINGLE, but corroborated)
• **SIG-20260425-dach-micro-saas-utility-lexoffice-price-fatigue** — recurring price + feature complaint, multi-company specifically (RECURRING)
• **SIG-20260425-dach-micro-saas-utility-circula-single-channel-distribution** — partner-led DACH B2B distribution (validates Lexoffice Marketplace channel)

Reasoning

Multi-company support is the #1 switch reason from Lexoffice per multiple comparison sites. We don't build another Lexoffice — we build an **overlay** that reads DATEV/Lexoffice-API exports from N source-accounts and gives consolidated view + cross-entity invoicing. Bridge-product: client keeps their preferred Lexoffice/sevDesk per entity, we eliminate the account-switching tax and duplicate data entry.

TAM is smaller than IDEA-015/016 (30-60k vs 200-800k), BUT pain-severity and WTP are much higher. Serial founders currently pay €40-100/mo on duplicate Lexoffice tariffs; €29/mo flat is economically obvious even at 2 entities. Distribution advantage: this audience is active on Twitter-DE, gruenderszene RSS, LinkedIn DACH-founder networks — narrow targeted reach.

Build complexity (multi-source sync + cross-entity invoicing logic) is the highest in this cell at 14 days, but that's the moat that protects the category from quick-clone entries.

Quick competitive read

5 profiled competitors (CMP files):

• **DATEV Unternehmen online** — €17-70/mo per Mandant via StB; Kanzlei-routed, not founder-self-service.
• **Lexware financial office** — €49-149/mo Premium has multi-Mandant 5 entities; we are 5.1x cheaper, plus cross-entity invoicing UI.
• **Agenda Software** — €65-95/mo per workstation Kanzlei-software; different market.
• **sevDesk** — no native multi-Mandant, requires N accounts; €13.90×N quickly exceeds our €29 flat.
• **FastBill** — same single-entity-per-account problem; weak defensive moat.

Market density: **medium-high upmarket but white-space at founder-self-service segment**. Lexoffice has explicit gap (per SIG-multi-company-blocker), DATEV products are StB-only, sevDesk/FastBill have no multi-Mandant. Build complexity (14 days, multi-source sync) is the moat. Competitive_pressure: 7 (medium-high).

Initial pricing hypothesis

€19/mo Starter (≤2 entities) → €29/mo Pro (≤5 entities, cross-entity invoicing, AI-matching, GoBD-archive) → €59/mo Holding (≤10 entities, 3 seats, custom reports). Upper end of the DACH developed $10-100/mo band — justified by serial-founder audience with €60-150k+/yr revenue.

Distribution hypothesis

LinkedIn DACH-founders + Twitter-DE founder community + gruenderszene/deutsche-startups RSS content marketing on Holding-Aufbau + VGSD partnership + Lexoffice Marketplace listing (per SIG-circula one-partner-ARR pattern) + cold-email targeted at Crunchbase/Dealroom DACH portfolio-founders.