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Home/Guide
Guide & Tips

Invoicing & Accounting Guide

Practical articles on e-invoicing, taxes, and financial management for freelancers and companies.

IT Freelancer Invoice in Germany: Requirements & Abroad
#IT freelancer6 min read

IT Freelancer Invoice in Germany: Requirements & Abroad

How IT freelancers write German invoices: mandatory details, hourly rates and milestones, EU and non-EU clients, and e-invoicing from 2027.

Redaktion Solobuch

Oct 13, 2026

GoBD-Compliant Invoice Archiving: 2026 Guide
#GoBD6 min read

GoBD-Compliant Invoice Archiving: 2026 Guide

How do you archive invoices in a GoBD-compliant way? Retention periods, the key principles - and why no official "GoBD certificate" exists.

Redaktion Solobuch

Sep 27, 2026

How to Write an Invoice in Germany: A Beginner Guide
#Invoice8 min read

How to Write an Invoice in Germany: A Beginner Guide

Step-by-step guide for freelancers and the self-employed: how to start invoicing in Germany in 2026 - from tax registration to your first e-invoice.

Redaktion Solobuch

Sep 27, 2026

How to Create an XRechnung: 2026 Guide (Including from PDF)
#XRechnung7 min read

How to Create an XRechnung: 2026 Guide (Including from PDF)

How do you create a valid XRechnung? A step-by-step guide — plus why a PDF invoice cannot simply be converted automatically.

Serhii Makarov

Sep 20, 2026

Writing an Invoice as a Private Individual: When Is It Required?
#Invoice6 min read

Writing an Invoice as a Private Individual: When Is It Required?

Do private individuals have to write an invoice? When a receipt is enough, when you become a business — and what applies to tradesperson invoices.

Redaktion Solobuch

Sep 20, 2026

Calculating Skonto: Formula, Example & Effective Annual Rate
#Skonto6 min read

Calculating Skonto: Formula, Example & Effective Annual Rate

How to calculate Skonto (early-payment discount) correctly: formula for the discount amount and effective annual rate, plus an example and when Skonto is worth it.

Redaktion Solobuch

Sep 20, 2026

EÜR for Kleinunternehmer 2026: Process, Requirement & Template
#EÜR7 min read

EÜR for Kleinunternehmer 2026: Process, Requirement & Template

Do Kleinunternehmer have to file an EÜR (income statement)? Process, deadlines, mandatory details, and how it differs from the Kleinunternehmer threshold.

Redaktion Solobuch

Sep 20, 2026

Invoicing as a Photographer: Usage Rights & E-Invoicing Mandate
#Photographer3 min read

Invoicing as a Photographer: Usage Rights & E-Invoicing Mandate

How to write legally compliant invoices as a photographer. Everything about usage rights (7% vs 19% VAT) and the new 2025 e-invoicing mandate.

Redaktion Solobuch

Aug 27, 2026

DATEV EXTF 700 Explained: How to Cut Tax Advisor Costs
#DATEV3 min read

DATEV EXTF 700 Explained: How to Cut Tax Advisor Costs

What is the DATEV EXTF 700 format and how does it help freelancers and self-employed people in Germany reduce their tax advisor costs? A practical guide.

Redaktion Solobuch

Aug 25, 2026

Cancellation Invoices (Stornorechnung): How to Fix Errors
#Stornorechnung3 min read

Cancellation Invoices (Stornorechnung): How to Fix Errors

Made a mistake on an invoice? Learn how to legally issue a Stornorechnung in Germany under GoBD rules and cancel E-Invoices in 2026.

Redaktion Solobuch

Aug 17, 2026

Invoice Numbering Rules in Germany (GoBD & UStG)
#Invoice Number3 min read

Invoice Numbering Rules in Germany (GoBD & UStG)

How to structure your invoice numbers correctly in Germany. Avoid GoBD violations, missing gaps, and ensure E-Invoicing compliance in 2026.

Redaktion Solobuch

Aug 14, 2026

Reverse Charge Mechanism Explained: B2B Rules & E-Invoicing
#Reverse Charge5 min read

Reverse Charge Mechanism Explained: B2B Rules & E-Invoicing

What is the Reverse Charge mechanism in Germany & the EU? Rules for 2026, required invoice statements, VAT IDs, and XML codes for E-Rechnung.

Redaktion Solobuch

Aug 6, 2026

Successful Payment Reminders (Mahnung): B2B Tips & Templates
#Mahnung4 min read

Successful Payment Reminders (Mahnung): B2B Tips & Templates

How to write a Mahnung in Germany. Learn about the dunning process, B2B late fees (40-Euro Verzugspauschale), and how to automate it in 2026.

Redaktion Solobuch

Jul 19, 2026

How to Write a Correct Invoice in Germany: Mandatory Fields
#Invoice6 min read

How to Write a Correct Invoice in Germany: Mandatory Fields

Which mandatory fields belong on a B2B invoice in Germany? Avoid mistakes, protect your VAT deduction, and get ready for e-invoicing in 2026.

Redaktion Solobuch

Jul 17, 2026

E-Invoicing Mandate 2025–2028 in Germany: B2B Checklist
#E-Invoicing4 min read

E-Invoicing Mandate 2025–2028 in Germany: B2B Checklist

The German e-invoicing mandate is active! Use our comprehensive checklist to ensure your business is fully compliant with B2B regulations in 2026.

Redaktion Solobuch

Jul 14, 2026

Invoicing as a Kleinunternehmer in Germany (§ 19 UStG)
#Kleinunternehmer4 min read

Invoicing as a Kleinunternehmer in Germany (§ 19 UStG)

How to correctly issue invoices without VAT as a small business (Kleinunternehmer) in Germany. Includes mandatory requirements and the 2025 e-invoicing mandate.

Redaktion Solobuch

Jul 13, 2026

ZUGFeRD 2.3 & Factur-X Explained: The B2B Guide
#ZUGFeRD 2.34 min read

ZUGFeRD 2.3 & Factur-X Explained: The B2B Guide

Learn how ZUGFeRD 2.3 and Factur-X work. We explain profiles, B2B benefits in Germany, and how to prepare for the 2025 e-invoicing mandate.

Serhii Makarov

Jul 10, 2026

What is XRechnung? The Complete Guide for B2B
#XRechnung7 min read

What is XRechnung? The Complete Guide for B2B

Learn everything about XRechnung: definitions, formats, the 2025 e-invoicing mandate in Germany, and how to create compliant B2B electronic invoices.

Serhii Makarov

Jul 9, 2026