Advance and Final Invoices: How to Reconcile Differences Correctly

Anyone who works with advance payments or instalments eventually discovers the real challenge: it's not issuing the first invoice, but cleanly linking advance invoices to final invoices. A miscalculated amount, a forgotten VAT line, or a missing reference to the prepayment — and suddenly the accounts don't match on either side. This article shows you how to reconcile the difference between advance payment and final invoice correctly in Switzerland.

Why Final Invoices So Often Contain Errors

With advance payments, two accounting movements run in parallel: the customer's prepayment and the actual service delivery. Many invoice issuers simply deduct the advance amount from the total — without separately showing VAT or linking back to the advance invoice.

This leads to three typical problems:

• VAT errors: Tax is calculated on the difference instead of the full amount.
• Missing reference: The final invoice doesn't name the original advance invoice, making it harder to trace.
• Incorrect posting: On the customer's side, the prepayment lands on the wrong account because there's no assignment.

The Correct Structure: Step by Step

1. Issue the Advance Invoice

The advance invoice (also called a deposit invoice) is a full invoice with all mandatory fields. It contains:

• Invoice number, date, description of service
• The agreed advance amount in CHF
• VAT shown on the advance amount (e.g. 8.1% on CHF 5'000 = CHF 405)
• A note that this is an advance payment (e.g. "Advance payment per order dated…")

The advance invoice establishes a tax obligation when the payment is received, not when the work is completed. This is especially important for VAT reporting under the cash basis method.

2. Build the Final Invoice Correctly

The final invoice shows the total contract value and deducts the advance invoices already paid. The structure looks like this:

Item	Amount (excl. VAT)
Total service per contract	CHF 20'000.00
Less: Advance payment 15.03.2026 (Invoice No. 2026-011)	CHF −5'000.00
Balance due	CHF 15'000.00
VAT 8.1% on CHF 15'000	CHF 1'215.00
Amount due	CHF 16'215.00

Important: The link only works if the VAT on the final invoice is shown in a way that matches the already-taxed advance amount. If VAT was already remitted on the advance invoice, that same service must not be fully taxed again on the final invoice.

3. Multiple Advance Invoices

For larger projects, there are often two or three partial payments before the final invoice. In this case, list each advance invoice separately — with invoice number, date, and amount excluding VAT. The VAT line on the final invoice then applies only to the remaining balance not yet taxed.

VAT: Accrual vs. Cash Basis

The method you use to report VAT affects when tax on advances becomes due.

Cash basis (Vereinnahmte Entgelte): VAT becomes due as soon as payment is received. An advance payment therefore triggers an immediate VAT obligation. This is the more common method for smaller SMEs and freelancers.

Accrual basis (Vereinbarte Entgelte): VAT becomes due as soon as the invoice is issued — regardless of payment timing.

If you're unsure which method applies to you or whether switching makes sense, the Swiss VAT basics 2026 — rates, duties and special rules provides a helpful comparison of both methods.

Accounting on the Service Provider's Side

From an accounting perspective, an advance payment flows through a clearing account:

1. Payment received: Debit Cash / Credit Advance Received (Liability)
2. Service delivered: Debit Advance Received / Credit Revenue
3. Final invoice: Only the balance is posted as a receivable

This structure prevents posting advance payments directly as revenue before the work is done — a common mistake that distorts year-end results.

What Belongs on the Final Invoice: Checklist

Before sending the final invoice, check these points:

• All mandatory fields present (invoice number, date, address, VAT ID, VAT rate)
• Reference to each advance invoice with number and date
• Total amount clearly shown before deductions
• VAT calculated only on the balance not yet taxed
• QR-IBAN or IBAN correct, amount matches remaining balance
• Payment terms clearly defined

If you create invoices directly in your browser, you can implement this structure using the SnapBill app, which supports advance payments as separate line items and calculates the outstanding balance automatically.

Common Special Case: Advance Exceeds Final Invoice Amount

If a project costs less than originally quoted, advance payments together may exceed the actual contract value. In this case, issue a credit note — not a new invoice. The credit note references the advance invoice, shows the overpaid amount, and displays VAT correctly. Without a credit note, you have an open liability on the books that isn't covered by any invoice.

At a Glance

• The final invoice always shows the total contract value and deducts advance invoices as separate line items.
• VAT on the final invoice is calculated only on the balance not yet taxed.
• Each advance invoice must be referenced on the final invoice with number and date.
• Advance payments belong on a clearing account from an accounting standpoint, not directly to revenue.
• If less is delivered than paid, a credit note closes the matter correctly.
• The complete invoice structure with all mandatory fields is described in the Swiss invoice template — all required fields in one place.

With a clearly structured final invoice, you avoid follow-up questions from customers, simplify posting on both sides, and ensure your VAT reporting is correct — with no corrections needed later.