Proposals & Invoices · Article 5.2
The 4 delta branches: Δ+, Δ−, Δ=0, Δ_REFUND
Every signed amendment falls into one of four branches based on (a) the sign of the cost change and (b) whether the proposal was already paid. Each branch fires a different document chain. This is the central conceptual map for the entire amendment system.
The four branches come from a single subtraction: delta = revised_total − original_total, with one extra check (was the original deposit already paid?). Each branch is a distinct legal path producing a distinct document set. You don't pick the branch manually — Clozo computes it from the line items you put in the wizard. But understanding the four shapes lets you predict exactly which PDFs and emails will appear after signing.
Step by step
Read the wizard's "Delta" indicator on Step 2.
It surfaces the sign and magnitude before you send. Green for Δ+, amber for Δ=0, red for Δ−, "Refund: €X" for Δ_REFUND.
Anticipate the document set.
If the wizard says Δ_REFUND, expect three new docs: Stornorechnung, Berichtigung der Anzahlungsrechnung, and a Gutschrift. The Documents dropdown will populate within 30 seconds of signing.
Anticipate the email
Δ+ and Δ− trigger a "Signed amendment + new invoice" email with a Pay-now CTA. Δ=0 sends a quieter "Signed amendment" confirmation. Δ_REFUND sends a "Refund issued" email referencing the credit note.
Anticipate the proposal status.
Δ_REFUND full → proposal will close to
Paid(legally settled) once Stripe confirms the refund. Δ+ → proposal moves to (or stays in)Awaiting final payment. Δ=0 → no status change.
On the Step 3 preview the wizard shows the Old vs New side-by-side, the delta tag (+€500.00, −€500.00, same, or Refund €1,200.00), and a contextual warning if the branch is Δ_REFUND ("This amendment will trigger an automatic refund — make sure the line items are correct before sending"). After signing, the Documents dropdown fills with the appropriate new docs (Storno + INV at minimum; plus DCR + CRN for refund branches).
Why this works this way
Why split out Δ_REFUND from Δ−? Because the legal documents are different. Δ− means "the contract is now smaller but the client still owes you something." Δ_REFUND means "the contract is now smaller and you owe the client back part (or all) of what they already paid." That second case requires a Berichtigung der Anzahlungsrechnung (DepositInvoiceCorrection) — a specific German VAT artefact under §17 UStG that formally corrects the original Anzahlungsrechnung (deposit invoice). Without it, the original deposit invoice's VAT line stays in your books overstated; the tax office can disallow the correction and force you to remit the full original VAT. Equivalent obligations apply under EU VAT Directive Art. 90 (general principle) and per-country implementations: BTW Art. 29 Wet OB (Netherlands), CGI Art. 272 (France), Art. 89 LIVA (Spain), Ustawa VAT Art. 106j (Poland).
The Δ=0 branch exists for cases where the legal scope changed but the money didn't — for example, swapping one deliverable for another of equal value, or correcting a description error after the contract was signed. The new invoice carries revision=v2 (or v3, v4...) and the old one is stornoed; the audit trail shows that the contract evolved without the financial total moving.
Troubleshooting
Keep reading
Proposals & Invoices
Creating an amendment (the 4-step wizard)
The amendment wizard at `/proposals/{id}/amend` walks you through line items, reason, preview, and email — in that order. Five minutes for a simple change, ten minutes for a complex one. The client doesn't see anything until you click Send on Step 4.
Proposals & Invoices
Why a signed amendment issues two new documents (Storno + new INV)
Every signed amendment that touches the financial side of the contract generates at minimum two new documents: a Stornorechnung (cancellation invoice) for the old final invoice, and a fresh active FinalInvoice with revised numbers. This is required by GoBD §147 AO and parallel EU rules — never an arbitrary Clozo choice.
Refunds & Notifications
When refunds happen: the Δ_REFUND amendment branches
A refund in Clozo is always tied to a Δ_REFUND amendment branch — partial (revised total smaller than deposit paid) or full (revised total at zero). The amendment is the legal trigger; the refund is the cash consequence.
Refunds & Notifications
Storno vs Berichtigung vs Gutschrift: three documents, three jobs
Three German VAT documents commonly confused with each other, each with a specific legal job and a specific moment when Clozo issues it. EU equivalents have similar names and identical purposes. Mixing them up is a frequent topic in support tickets — and a frequent cause of accountant pushback.