Invoicing software for small businesses must produce invoices with all mandatory details, number them sequentially and uniquely, work without showing VAT under § 19 UStG and archive finished invoices unalterably. This article summarises what to look for. It is not tax advice; for your individual case ask your tax adviser.
Which mandatory details must an invoice contain?
The mandatory details are set out in § 14(4) UStG. They include the name and address of supplier and recipient, your tax number or VAT identification number, the date of issue, a sequential, uniquely assigned invoice number, the quantity and type of the service, the date of the service and the consideration.
As a small business you show no VAT. A note such as "Under § 19 UStG no VAT is charged" is usual. If you nevertheless show the tax separately, it may be owed under § 14c UStG. For invoices up to €250 gross, § 33 UStDV allows reduced details. Since 2025 the limit for the small-business regulation is €25,000 of turnover in the previous year and €100,000 in the current year.
What must invoicing software be able to do?
The table shows the main requirements with a check question for each.
| Requirement | Why | Check question |
|---|---|---|
| Template with mandatory details | Faulty invoices cause queries | Are all mandatory fields and the § 19 note included? |
| Sequential, unique numbers | Gaps and duplicates stand out in audits | Does the software assign numbers itself? |
| Locking and cancellation | Altered records endanger proper bookkeeping | Is an invoice locked after sending? |
| Archive and export | Retention and handover to the tax adviser | Is there an export, such as CSV or DATEV format? |
| Payment status and reminders | Open items cost liquidity | Does it show due and overdue invoices? |
| Switch to regular taxation | The turnover limit can be exceeded | Can VAT be switched on later? |
The GoBD principles (traceability, completeness, unalterability) apply to tax-relevant records even for income-surplus accounting. Good software makes compliance easier but does not remove your responsibility. Document how you create, file and back up invoices.
How do you deal with the e-invoice?
Since 2025, businesses in Germany must be able to receive e-invoices in dealings with other businesses. An e-invoice is a structured data set, for example in XRechnung or ZUGFeRD format; a simple PDF does not count. The obligation to issue them is being phased in. Small businesses are exempt from it. Still set up a mailbox where e-invoices can arrive and check whether your software can read them. The rules keep evolving; check the current position with your tax adviser.
When is a custom solution worthwhile?
Standard software is enough as long as your process is simple. A custom solution pays off when the invoice should arise automatically from an enquiry, booking or order, when customers retrieve invoices in a portal or when several systems work together. At WebDrift such business systems start at €3,900 plus €149 a month for hosting and support. All prices are final prices under § 19 UStG. How invoices fit into a wider process is shown in How to digitise business processes, and the path from enquiry to customer management is described in Why your website should feed a CRM.
- Template contains all mandatory details and the § 19 UStG note
- Invoice numbers are assigned sequentially and uniquely
- Sent invoices cannot be changed unnoticed
- Archive, backup and export for the tax adviser are clarified
- Receipt of e-invoices is prepared
- Turnover limits are monitored, switching to regular taxation is possible
Conclusion: clean, sequential, traceable
Good invoicing software takes routine work off your hands and helps avoid errors. Start simply, watch numbers, mandatory details and archive, and discuss doubtful cases with your tax adviser. If you want to tie invoices into an automated process, describe your process.
