Rechnung App: Best Invoice App for Austrian & German Freelancers

Searching for a Rechnung app usually means you’ve hit the wall with manual invoicing. Maybe you’ve been creating Rechnungen in Word or Excel, carefully updating invoice numbers by hand, double-checking your USt calculations, and spending way too long on something that should take minutes, not the better part of an hour.

German-speaking markets — Austria and Germany in particular — have specific invoicing requirements that generic international tools often get wrong. The Umsatzsteuer rates, Kleinunternehmer exemptions, required fields, and formatting conventions all matter. An invoice app that doesn’t understand these details creates more problems than it solves.

This guide compares the best options for Austrian and German freelancers, covers the legal requirements you can’t skip, and shows you what to look for in a Rechnung app that actually fits your workflow.

What Austrian and German Law Requires on a Rechnung

Before comparing apps, you need to know what a legally compliant Rechnung must include. The requirements come from §11 UStG in Austria and §14 UStG in Germany, and they’re remarkably similar.

Required Fields (Both Countries)

Every Rechnung must contain:

1. Your complete business details — name, address, and UID-Nummer (Austria) or USt-IdNr (Germany)
2. Client’s complete details — name and address (for invoices over €400 in Austria, all invoices in Germany for B2B)
3. Sequential invoice number — Rechnungsnummer, consecutive without gaps
4. Invoice date — Rechnungsdatum
5. Delivery or service date — Leistungsdatum or Lieferdatum (can differ from invoice date)
6. Clear description of goods or services — Bezeichnung der Leistung
7. Net amount — Nettobetrag
8. USt rate and amount — 20% in Austria, 19% in Germany (standard rates)
9. Gross total — Bruttobetrag

Austria-Specific Requirements

• UID-Nummer (ATU + 8 digits) required on invoices over €400 gross
• Kleinunternehmerregelung exemption if annual revenue under €35,000: invoices must state the exemption explicitly
• Reverse Charge for certain B2B services — client pays the USt directly
• Standard USt: 20%, reduced: 10% (food, books, cultural events) or 13% (specific categories)

Kleinunternehmer note on Austrian invoices:

“Umsatzsteuerbefreit — Kleinunternehmer gem. § 6 Abs. 1 Z 27 UStG”

Germany-Specific Requirements

• USt-IdNr (DE + 9 digits) for EU cross-border transactions
• Steuernummer for domestic invoices (your local tax office number)
• Kleinunternehmerregelung if annual revenue under €22,000: must include exemption reference
• Standard USt: 19%, reduced: 7% (food, books, public transport, cultural)

Kleinunternehmer note on German invoices:

“Gemäß § 19 UStG wird keine Umsatzsteuer berechnet.”

Kleinbetragsrechnung (Small Invoice Simplification)

For invoices under €250 gross (Germany) or €400 gross (Austria), you can issue a simplified invoice with fewer requirements:

• Your business name and address (full details)
• Invoice date
• Description of goods/services
• Gross amount including USt
• USt rate applied

You don’t need the client’s details or a separate USt breakdown. This is useful for small, frequent transactions — but most freelancers bill above these thresholds regularly.

The Invoice App Landscape for DACH Freelancers

Let’s look at what’s actually available and how each option stacks up.

SevDesk

What it is: A German cloud-based accounting platform with invoicing

• Strengths: Full GoBD compliance, DATEV export, integrated banking, built for German tax requirements
• Weaknesses: Complex for “I just need to send invoices” users, desktop-oriented interface, monthly cost starts at €8.90
• Best for: Freelancers who want invoicing + full bookkeeping in one platform
• Mobile experience: Has an app, but it’s clearly a mobile version of a desktop product

Billomat

What it is: German invoicing and accounting software

• Strengths: Good German/Austrian compliance, recurring invoices, client portal
• Weaknesses: Interface feels dated, mobile app is limited, starts at €9/month
• Best for: Small businesses with regular clients who need ongoing billing
• Mobile experience: Basic — you can view and send invoices but creation is clunky on mobile

Debitoor/SumUp Invoices

What it is: Simple invoicing tool (rebranded under SumUp)

• Strengths: Clean interface, easy onboarding, payment processing integration
• Weaknesses: Limited customization, basic reporting, tied to SumUp ecosystem
• Best for: Retail and service businesses already using SumUp for payments
• Mobile experience: Decent but focused on point-of-sale more than professional invoicing

Lexoffice

What it is: Comprehensive German accounting tool by Haufe

• Strengths: Full GoBD compliance, tax advisor integration, comprehensive features
• Weaknesses: Expensive (€13.90+/month), overkill for simple invoicing, steep learning curve
• Best for: Growing businesses that need full accounting, not just invoicing
• Mobile experience: Functional but complex

InvoiceZap

What it is: Mobile-first invoice creation app for iOS

• Strengths: Creates invoices in 30 seconds, truly mobile-native, clean professional output, works offline
• Weaknesses: iOS only, no integrated accounting, no DATEV export, no direct USt filing
• Best for: Freelancers and service professionals who want speed and simplicity on their Apple devices
• Mobile experience: Built for mobile from the ground up — this is the primary interface, not an afterthought

Quick Comparison

The honest breakdown: If you need a complete accounting solution with tax filing and DATEV integration, SevDesk or Lexoffice are stronger choices. If you need fast, professional invoice creation on your phone — especially for on-site service work — InvoiceZap is significantly faster and simpler.

Many Austrian and German freelancers actually use both: a fast mobile app for creating and sending invoices, and an accounting tool for bookkeeping and tax prep.

Speed Test: Creating a Rechnung

I timed the process of creating a standard freelancer invoice (3 line items, client details, USt calculation) across platforms:

The invoice: Web design project for a Vienna-based client, 3 services (design, development, SEO setup), 20% USt, payment terms 14 days.

SevDesk: 4 minutes 12 seconds

• Navigate to invoices → new invoice (15 sec)
• Search and select client (20 sec)
• Add 3 line items with descriptions (90 sec)
• Verify USt calculation and rate (15 sec)
• Adjust payment terms and notes (30 sec)
• Preview and send (42 sec)

Lexoffice: 5 minutes 38 seconds

• Navigate to new invoice (20 sec)
• Enter client details (45 sec — first time; 15 sec returning)
• Add line items with product codes (120 sec)
• Review tax settings (30 sec)
• Add payment information and notes (45 sec)
• Preview, adjust formatting, send (58 sec)

InvoiceZap: 34 seconds

• Open app, tap new invoice (3 sec)
• Select client from saved contacts (5 sec)
• Add 3 saved service items (12 sec)
• Review auto-calculated total (4 sec)
• Send (10 sec)

The caveat: First-time setup in InvoiceZap takes 5-10 minutes (entering business details, saving clients, creating service items). After that, the speed advantage compounds with every invoice.

For freelancers sending 10+ Rechnungen monthly, that’s roughly 45 minutes saved versus desktop tools. Over a year, that’s 9 hours — more than a full working day reclaimed.

Setting Up Your Rechnung Workflow

For Austrian Freelancers (Einzelunternehmer)

Your checklist:

1. Register your UID-Nummer with the Finanzamt if your annual revenue exceeds €35,000 (or opt in voluntarily)
2. Decide on Kleinunternehmer status — below €35,000 you can skip USt, but you also can’t reclaim input tax
3. Set up sequential numbering — most Austrian freelancers use YYYY-NNN format (2026-001, 2026-002…)
4. Prepare your standard Leistungsbeschreibungen — clear, specific service descriptions
5. Configure your payment details — IBAN (AT + 18 digits), bank name, payment terms

Payment terms standard in Austria:

• 14 Tage netto (14 days net) — common for freelancers
• 30 Tage netto — standard for larger projects
• Sofort fällig (due immediately) — for on-site services

For German Freelancers (Freiberufler)

Your checklist:

1. Get your Steuernummer from your local Finanzamt
2. Apply for USt-IdNr if you have EU clients
3. Determine Kleinunternehmer eligibility — under €22,000 annual revenue
4. Understand GoBD requirements — your invoicing records must be tamper-proof, traceable, and stored for 10 years
5. Set up DATEV-compatible export if your Steuerberater uses DATEV (most do)

GoBD note: Germany’s GoBD regulations require that invoice data be stored in an unalterable format. If you use an app for invoice creation, make sure you also export and archive properly. PDF copies sent via email generally satisfy the requirement, but check with your Steuerberater.

Kleinunternehmer: Special Invoicing Rules

A significant percentage of Austrian and German freelancers operate under the Kleinunternehmerregelung. If that’s you, your Rechnungen look different:

What Changes

• No USt charged — you don’t add 20% (AT) or 19% (DE) to your invoices
• Mandatory exemption note — you must explain why there’s no USt
• No Vorsteuerabzug — you can’t reclaim USt on business purchases
• Simpler bookkeeping — no USt-Voranmeldung required

Practical Impact on Your Invoice

Standard freelancer Rechnung (with USt):

Kleinunternehmer Rechnung (without USt):

The Kleinunternehmer version is simpler but — counterintuitively — sometimes costs you clients. Some businesses prefer vendors who charge USt because they can reclaim it. Something to consider when deciding whether to opt into USt voluntarily.

On-Site Invoicing: Where Mobile Apps Shine

For Austrian and German service professionals — Handwerker, IT-Dienstleister, Berater doing on-site work — the ability to create and send a Rechnung immediately after finishing a job is a genuine competitive advantage.

The old workflow:

1. Finish the job on-site
2. Drive home/back to office
3. Open laptop, find template
4. Create Rechnung from memory (hope you remember everything)
5. Send it the next day (or worse, next week)

With a mobile Rechnung app:

1. Finish the job
2. Pull out your iPhone, create Rechnung in 30 seconds
3. Send it while still with the client
4. Client sees the Rechnung immediately — fresh in their mind, faster payment

Freelancers who invoice on-site consistently report faster payment. The psychology is straightforward: the client just received the service, they’re satisfied, and the invoice arrives while the value is still fresh. Waiting days or weeks lets that urgency fade.

InvoiceZap was built for exactly this scenario. The entire interface assumes you’re on a phone, possibly between appointments, and need to get an invoice out fast. No laptop required, works offline if you’re on a job site with poor reception.

Download InvoiceZap and try creating your first Rechnung — the 3-day trial gives you full access to every feature.

Austrian vs. German Invoice Differences

If you freelance across both countries (common in the DACH region), keep these differences straight:

The EU E-Invoicing Trend

Both Austria and Germany are moving toward mandatory B2B e-invoicing, following Italy’s lead. Germany has already begun implementation, with B2B e-invoicing becoming mandatory in stages starting 2025. Austria will follow under the EU ViDA (VAT in the Digital Age) directive.

What this means for you: your invoicing system needs to support structured data formats (XRechnung in Germany, likely similar in Austria). Apps and tools that can export in these formats will become essential, not optional.

Choosing the Right Rechnung App for Your Situation

You Need Full Accounting → SevDesk or Lexoffice

If your Steuerberater wants DATEV exports, you need quarterly USt-Voranmeldung automation, and you want bookkeeping + invoicing in one place, go with a full platform. The learning curve pays off at scale.

You Need Fast Invoice Creation → InvoiceZap

If your primary pain is “I spend too long creating invoices and I want it done in seconds,” InvoiceZap is purpose-built for that. Pair it with a simple bookkeeping tool or your Steuerberater’s preferred system for the accounting side.

You Need Payment Processing → SumUp Invoices

If you need integrated card payments and invoicing (retail, hospitality, events), SumUp’s ecosystem ties together well.

You’re Just Starting Out → Start Simple

Don’t over-engineer it. A Kleinunternehmer sending 5 invoices a month doesn’t need Lexoffice. Start with InvoiceZap or a template, and upgrade to a full accounting platform when your business complexity demands it.

Your Rechnung, Faster

German-speaking freelancers sometimes over-complicate invoicing because the legal requirements feel intimidating. The USt rules, Kleinunternehmer thresholds, mandatory fields, and retention requirements create the impression that invoicing must be a time-consuming administrative burden.

It doesn’t have to be. Once you understand the requirements (and you now do), the actual creation process should be fast. Save your business details. Save your client information. Save your standard services. Then each new Rechnung is just selecting and sending.

InvoiceZap handles all of this on your iPhone, iPad, or Mac. Set up once, invoice in 30 seconds every time after. The 3-day trial lets you test every feature with real invoices — no limitations, no watermarks, no “upgrade to unlock” gates.

Start your free trial of InvoiceZap and create your first professional Rechnung in under a minute.

Tags: