Invoicing as flexible as your projects – by hours, products, flat fees or mixed. With timesheets, multiple business units and e-invoices straight from the system. Without the weight of a big ERP.
For companies whose invoices don’t fit a standard template – and who don’t want to start a big ERP project.
You bill by the hour and need the timesheet as proof for your client.
One system for multiple business units – each with its own number range, bank details and texts.
Mixed VAT rates, reverse charge, flat fees and commissions – without spreadsheet acrobatics.
Create e-invoices directly, without introducing a big ERP.
The typical flow in four steps – automated where it helps, with your approval where it counts.
Collect hours in a timesheet – by category or by person – and approve them internally. The budget traffic light shows how much of the order has been used.
The approved timesheet becomes an invoice draft based on the project’s billing method. Every line item stays fully editable.
Finalising assigns the sequential invoice number. Sent by email as a ZUGFeRD PDF or XRechnung – with the timesheet attached automatically.
Documents go to DATEV Unternehmen online via upload email. Bookkeeping and payment reconciliation stay with your tax advisor.
The dashboard shows where you stand since the start of the year: revenue, margin and the development per business unit – straight from finalised documents, no exports, no spreadsheets.
Gross from finalised invoices and incoming credit notes – plus the current month, the previous month and the last six months as bars.
Net minus the costs recorded per invoice, in euros and as a percentage. Plus costs year to date and the margin per month.
All business units side by side, sorted by revenue. Hover over the bars for details.
Revenue and margin are visible to admins and accounting only – each for the business units they are enabled for. The interface is in German; all figures are sample data.
Built from our own billing practice – including the special cases real projects bring.
Hours, products, flat fees, commissions or quantity blocks with subtotals – freely combined in one invoice. Item master and free text, line items also via Excel import.
Recording by category or by person, internal approval and a budget traffic light. AI reads hours from external timesheet PDFs and fixes spelling and grammar in activity descriptions at the click of a button.
ZUGFeRD as a hybrid PDF for business customers, XRechnung for public-sector clients including Leitweg-ID – both following EN 16931, from the same data.
Multiple VAT rates in one invoice, shown separately. Reverse charge, intra-community and non-taxable supplies with the matching notice.
Invoice numbers are only assigned on finalisation – sequentially and per business unit. Discarded drafts leave no gaps, and only drafts can be deleted. Finalised documents cannot be changed.
Several companies or brands under one roof, each with its own number range, bank details and standard texts. The dashboard shows revenue and margin per unit.
Email with CC/BCC, selectable PDF attachments and a send log. Public document links with expiry date and access log – no customer login needed.
Invoices and incoming credit notes are sent to DATEV Unternehmen online via upload email, including the original PDF. No exporting, no manual uploads.
Via REST API, an online shop for example can create invoices automatically. Through an MCP server, AI assistants such as Claude can look up documents and open items – read-only, enabled per user and with a kill switch.
S4U-ERP is not a jack of all trades. It takes care of invoices, documents and timesheets – and hands everything else to the systems built for it.
Want to keep your existing invoicing software? Then pdf-zugferd.de converts your existing invoice PDFs into e-invoices. Background on the transition in our article on the German e-invoicing mandate (in German).
You don’t get a software package to install yourself, but a running system – configured for your workflows.
Every customer gets their own system with its own database – no shared platform.
Operated on servers in a German data centre.
We set up master data, logo, number ranges and billing methods – and add special cases where needed.
Maintenance and further development from a single source – by the team that built the system.
We do our own invoicing with S4U-ERP. The system grew out of everyday work at S4U GmbH – with hourly billing, commissions, public-sector clients and several business units.
We’ll show you the system with sample data – by phone with screen sharing. Pricing depends on scope and customisation; you’ll receive a quote after our first conversation.