Billing and Invoicing

Proposal Air includes a full invoicing module built for freelancers and small businesses in Germany. Convert accepted proposals into invoices, send them electronically, and track payment status — all while staying compliant with German tax and bookkeeping requirements.

Creating Invoices

Generate invoices directly from accepted proposals or create them from scratch. Each invoice is assigned a sequential invoice number following the RE-YYYY-NNNN format (e.g., RE-2025-0042). The prefix and starting number are configurable in your organization settings.

Configurable Fields

Every invoice includes the following fields, all pre-filled from proposal data where available:

• Invoice date — defaults to today, adjustable
• Due date — based on your configured payment terms (e.g., 14 or 30 days)
• Delivery date or delivery period — single date or date range for the service period
• Invoice number — auto-generated, sequential
• Reference / PO number — optional, for client-side tracking

Line Items and Pricing

Line items carry over from the proposal. Each item includes a description, quantity, unit, unit price, and tax rate. The invoice calculates:

• Net subtotal per item
• Applicable VAT per tax rate
• Gross total

For proposals with tiered or optional pricing, only the items the client selected are included.

VAT and Small Business Regulation

Invoices automatically apply the correct tax treatment based on your organization settings:

• Standard VAT — 19% or 7% (reduced rate) displayed per line item, with a VAT summary at the bottom
• Small business regulation (§19 UStG) — no VAT charged; the legally required notice is automatically added to the invoice
• Reverse-charge (EU B2B) — VAT-exempt with the required reverse-charge notice and client VAT ID

Credit Notes

If an invoice needs to be partially or fully reversed, create a credit note referencing the original invoice number. Credit notes follow the same numbering scheme and are linked to the original invoice in the history.

Sending and Delivering Invoices

Once an invoice is finalized, you can deliver it to your client electronically — no printing or postal mail required.

Email Delivery

Send invoices directly from Proposal Air via email. Before sending, you see a preview of the email including:

• Subject line (customizable)
• Message body with invoice summary
• Attached PDF

The client receives the invoice as a PDF attachment and a link to view it online.

Public Invoice Link

Every invoice has a unique, secure URL that the client can access without logging in. The page shows the full invoice with a download button. Links remain active for the configured retention period.

Export Formats

EN16931 E-Invoicing

ZUGFeRD exports conform to the EN16931 European e-invoicing standard. This means your invoices can be automatically processed by any accounting software that supports the standard — including DATEV, Lexware, and sevDesk. Starting 2025, e-invoicing capability is increasingly required for B2B transactions in Germany.

Invoice History and Management

All invoices are stored in a searchable, paginated list. Filter by status, client, date range, or invoice number to quickly find what you need.

Invoice Status Workflow

Each invoice moves through a defined set of statuses:

Status changes are logged with a timestamp so you always know when an invoice was sent, paid, or cancelled.

Download History

Every version of an invoice PDF is retained. If you regenerate a PDF after corrections, previous versions remain accessible in the document history.

Audit Trail and GoBD Compliance

German bookkeeping regulations (GoBD) require that business records be traceable and unalterable. Proposal Air supports this by:

• Logging every status change with timestamp and user
• Retaining all invoice versions (no silent overwrites)
• Providing sequential, gap-free invoice numbering
• Storing invoices for the legally required retention period (10 years for invoices under German tax law)

Online Payments via Stripe Connect

In addition to traditional invoicing, you can collect payments directly within proposals — before a formal invoice is even created.

Setup

Connect your Stripe account via Organization Settings → Payments. Proposal Air uses Stripe Connect (Express), so payments go directly to your Stripe account.

Payment Options in Proposals

When creating or editing a proposal, choose under "Payment Settings":

• Full payment — The client pays the full gross amount upon proposal acceptance
• Deposit — The client pays a configurable percentage (e.g., 50%) upon acceptance

The payment link is automatically displayed on the public proposal page once the client accepts the proposal.

Payment Status

Payment status is shown directly in the proposal overview. Stripe webhooks automatically update the status upon successful payment.

Compliance Overview

Proposal Air's invoicing module is designed with German and European regulatory requirements in mind:

Tips

• Customize your invoice number prefix — change it in organization settings to match your existing numbering (e.g., INV- or 2025-).
• Add your bank details — configure IBAN and BIC in your organization settings so they appear automatically on every invoice.
• Use ZUGFeRD for your tax advisor — if your Steuerberater uses DATEV, send them the ZUGFeRD PDF for seamless import.
• Set payment terms early — configure your default due date offset (14, 30, or 60 days) so every invoice has the correct deadline.
• Review before sending — use the email preview to double-check amounts, tax rates, and client details before delivery.

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Related Topics

• Taxes & Legal — VAT, small business regulation, and reverse-charge rules
• Getting Started — Set up your organization and create your first proposal
• Best Practices — Structure and mandatory details for proposals