Causation and proof: estimating loss under section 273 ZPO

The exact amount of a loss cannot always be proved by an invoice or a complete calculation. Austrian civil procedure addresses this situation in section 273 ZPO. It allows the court to estimate the amount where entitlement to compensation is established but the exact figure cannot be proved, or can only be proved with disproportionate difficulty.

The provision is not a substitute for proving the entire damages claim. It must first be established that a party is entitled to compensation or another claim. Only then does the question of amount arise. Confusing these two levels can lead to an unclear claim and an incomplete schedule of loss.

This article explains when section 273 ZPO can matter in Austrian damages cases, which indications support an estimate and why a judicial estimate does not automatically confirm the amount requested.

Under section 273(1) ZPO, it must first be established that a party is entitled to compensation for a loss or has another claim. In addition, proof of the disputed amount must be impossible or possible only with disproportionate difficulty. Only this combination permits the court to determine the amount according to its free conviction.

The court may act on a party’s request or on its own initiative. It may disregard an offered piece of evidence if investigating the exact amount would be disproportionate to the importance of the open issue. The relevant circumstances must nevertheless be sufficiently tangible.

Section 273 ZPO therefore does not make evidence generally unnecessary. Anyone seeking an estimate should set out the loss items, their connection with the event and the available indications. The guidance on evidence and limitation helps structure this distinction.

The central distinction is that section 273 ZPO concerns the amount, not automatically the legal basis of the claim. Whether there was a breach of duty, whether the event caused the loss and whether the item is legally recoverable must be decided separately.

After a traffic accident, for example, liability may be established in principle while the precise amount of lost earnings or necessary repairs is difficult to determine. Conversely, a precise invoice cannot cure an unresolved causal connection between the event and the claimed item.

For each item, record the event, legal basis, concrete consequence and amount. The claim check can help organise the parties and loss items before a detailed assessment.

An estimate is not made without a basis. The court must consider the evidence taken and the concrete facts established in the proceedings. These may include invoices, offers, earlier prices, comparable objects, photographs, time records, medical documents or comprehensible calculations.

The more clearly secure and disputed parts are separated, the more reliable the estimate can be. In repair costs, for example, the work required may be undisputed while individual labour or material rates remain contested. For loss of use, the duration and actual use may require separate assessment.

A bare statement that the loss is “approximately” a certain amount is insufficient. Explain which facts are secure, which values are being compared and why a further exact investigation would be disproportionate. The damage documentation check supports this organisation.

Section 273 ZPO permits an estimate only for the amount whose exact proof is especially difficult or disproportionate. The court can therefore focus evidence on decisive facts. Clear parts of the loss should be separated from the uncertain remainder.

The party must still provide all documents that can reasonably be obtained. A deliberate failure to present evidence cannot be replaced by referring to section 273 ZPO. Expert evidence may also be appropriate where a technical or medical question can clarify the amount.

The relevant question is not whether an estimate is more convenient. It is whether, despite established entitlement, determining the exact amount would require an effort out of proportion to the importance of the disputed item. That explanation belongs in the pleadings.

Section 273(2) ZPO concerns several claims brought in the same action where individual claims are insignificant compared with the total and fully clarifying their circumstances would involve disproportionate difficulty. The same applies to individual claims where the amount sought does not exceed 1,000 euros.

The 1,000 euro threshold does not mean that every small claim is automatically awarded. Entitlement and recoverability must still be established. The rule only simplifies deciding a relatively small or difficult-to-quantify amount.

Where there are several items, present them separately. A single combined amount makes it harder to see which parts are documented and which parts are to be estimated.

On 30 June 2026, the OGH principle RS0111576 recorded in RIS stated that an amount fixed under section 273 ZPO qualifies as a reviewable legal assessment. Applying the provision and fixing the amount are therefore not entirely beyond legal review.

RS0121220 also emphasises that an estimate based on life experience, human understanding and the results of the entire hearing generally has no significance beyond the individual case. An estimate is not a general tariff for similar losses.

The practical consequence is clear: set out the facts of the individual case carefully. A similar loss item in another case may provide a comparison point, but it does not replace the evidence concerning your event, documents and amount.

A common mistake is asking for an estimate even though liability or causation has not been established. Another is presenting an unexplained total that does not identify the individual loss items or their documents.

Avoid contradictory calculations as well. If one item is supported by an invoice, it should not also be based on a broad comparison value without explaining the difference. A failure to explain why exact investigation would be disproportionate also weakens the request.

Arrange the documents chronologically and connect each figure with its basis. The guidance on personal injury and recovery costs complements the assessment of medical loss items.

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