Invoice 2026: what must be on it for legal compliance?

Your client just left and the next question already lies on the table: „Can I have a receipt?“ — In Austria we call this a Honorarnote (professional invoice), and it is more than a piece of paper. It triggers reimbursement from the health insurance fund, it is what tax authorities want to see, and it is your client's official record. Here is the precise list of mandatory fields — status May 2026, including everything new this year.

Honorarnote, invoice, receipt — what is the difference?

In Austria, freelance professionals use the term Honorarnote for the invoice for their own service. Legally it is an invoice under UStG §11 (Austrian VAT Act) — the mandatory fields are identical. Psychologists and therapists who fall under the VAT exemption are subject to additional rules.

Small-business exemption — what is the threshold?

The small-business threshold in Austria for 2026 is EUR 55,000 net annual turnover. Below this, you are exempt from VAT (UStG §6 (1) Z 27). For you this means:

• No VAT on the invoice — but you MUST include the note „VAT-exempt small business under UStG §6 (1) Z 27“
• No input-tax deduction — not even on business purchases
• VAT-ID optional — but useful if you regularly invoice businesses

Exception: Psychotherapeutic treatment is also exempt under UStG §6 (1) Z 19 (medical-treatment exemption) — even above EUR 55,000. Self-experience training, coaching and supervision do NOT fall under this exemption and become VAT-taxable above the threshold.

The 9 mandatory fields in detail

An invoice is only legally compliant if all of the following fields are present:

• 1. Full name and address of the service provider (your practice address)
• 2. Full name and address of the recipient
• 3. Invoice date (issue date)
• 4. Sequential invoice number — with no gaps (e.g. 2026-001, 2026-002 ...)
• 5. Service date or service period (e.g. „March 2026“ for consolidated invoices)
• 6. Description of the service (e.g. „Psychotherapy session 50 minutes“)
• 7. Quantity and unit price or total amount
• 8. Tax treatment — either VAT rate with amount or exemption notice
• 9. Payment terms (bank details, due date, payment method)

Additionally for insurance-reimbursable invoices from July 2026

• 10. ICD-10 code for the underlying disorder
• 11. Social security number (10-digit) of the client
• 12. Treatment start date for follow-up invoices

Recommended (not mandatory but practice-tested)

• VAT-ID for B2B invoices over EUR 400 gross
• VAT exemption notice for small businesses
• Payment reference (e.g. invoice number)
• Reimbursement note for out-of-network therapy (e.g. „ÖGK out-of-network rate 2026: EUR 33.70 per session“)

Example invoice with all fields

The 5 most common mistakes

1. Gaps in invoice numbering. If number 12 is missing between 11 and 13, the tax office will ask. Gaps are not allowed — even for cancelled invoices.
2. Missing VAT-exemption notice. Small businesses MUST include the exemption notice. Otherwise the invoice is challengeable.
3. Wrong service date. The invoice issue date is not the service date. Both must appear, otherwise the invoice is not accepted.
4. Recipient address as initials. „M.M., 1020 Vienna“ is not enough. The full name must appear — otherwise your client cannot use the invoice for tax or insurance purposes.
5. ICD-10 missing on insurance invoice. From July 2026 the invoice will be rejected without the code — even if all other fields are correct.

Template for your practice

You can write all of this in any word processor. But each invoice by hand takes 5–10 minutes — and at 80 sessions a month that adds up to 10 hours of admin. This is exactly what TimeInvoicer is for.

All 12 mandatory fields are in the template from the start. Nothing to forget. Nothing to maintain. The whole flow takes under a minute — because TimeInvoicer already knows from your calendar, your contacts and your last invoices what you need.

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