Flexible invoicing
Project Billing & Invoicing for Agencies
OS/ is the agency software that lets you create project invoices directly from within the project.
See outstanding and scheduled invoices at a glance, keep financial planning under control even on complex projects, and hand receipts straight to your accounting.
Simple Billing
Billing made simple
With OS/, you can leave paperwork and complexity behind: cost estimates and tracked hours are automatically incorporated into your project billing.
Invoices are generated with just a few clicks—leaving you free to focus on the project’s success.
Flexible invoicing
Which invoice types does OS/ support?
Whether down payments, progress invoices, or line-item billing — OS/ handles every type of project billing with ease, even on complex projects.
Accounting handover
Straight into your accounting software
With OS/ you create compliant outgoing invoices and transfer them directly to your accounting software.
No extra finance tools or middleware needed — everything in one place.
From hours to invoice
From tracked hours to invoice
Tracked time and approved cost estimates flow straight into billing, so nothing slips through.
Want to track project budgets and profitability too? See OS/ project controlling.
Free 6-week trial
Try OS/ for free with no obligation — with your entire team, full access to all features, and free support...
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Frequently Asked Questions / FAQ
In what format does OS create e-invoices?
OS/ generates e-invoices in ZUGFeRD format – a combination of human-readable PDF and machine-readable XML data in a single file that DATEV and tax advisors can process directly.
Do I need accounting software in addition to project billing?
No. Project billing, e-invoicing, and document workflow are integrated into the OS/ Agency software – all in one place.
Do I see planned and outstanding invoices?
OS/ shows planned and outstanding invoices per project – keeping your financial planning always up-to-date.
Can I transfer project invoices to DATEV?
Yes. OS/ generates GoBD-compliant sales invoices and, if desired, transfers them directly to DATEV, ensuring your data automatically reaches your tax advisor.
What invoice types does OS/ support?
OS/ supports down payments, progress invoices, and line-item billing – all as legally compliant e-invoices.