Cardano Collateral on Failed Scripts: Which ADA Can Be Charged?

Cardano collateral is ADA pledged for the ledger's failed Plutus-script execution path, not a second fee charged whenever a wallet displays an error. A phase-1 rejection does not consume collateral. If a phase-2 failure is recorded onchain, inspect the transaction's collateral and return output to determine what was actually charged.

Locate the failure before calculating a loss

Cardano uses two validation stages. The first checks structural conditions such as available inputs, signatures and value balance. The second evaluates Plutus scripts. The official failure guide distinguishes a build-time error, a node rejection and an onchain script failure. They should not all be described as a paid failed contract execution.

The ledger-validity explanation states that a phase-2-failing transaction can still be included, with collateral covering that path. Inclusion and its actual result therefore matter. A local script evaluation error alone does not prove that the network consumed anything from your wallet.

Normal fee and collateral answer different questions

A successful transaction pays its normal transaction fee. Collateral provides a way to cover failed phase-2 work without applying the intended script-controlled transfer. The Cardano collateral glossary describes collateral being taken instead of the normal transaction fee on that failure path. Do not automatically add the displayed normal fee to the collateral charge as two separate payments for the same result.

An ordinary ADA payment without Plutus execution is not the same workflow as a transaction spending a Plutus-controlled input. Seeing Cardano's collateral feature in a wallet does not mean every native transfer requires setting it aside. Conversely, a dApp request that includes scripts needs review of its actual transaction rather than assumptions copied from a simple send.

The amount required by the protocol depends on parameters and the transaction. This article does not prescribe a universal collateral deposit. Check the wallet's current request and network conditions. A support agent's demand to send a fixed activation payment to an unrelated address is not explained merely by using the word collateral.

Selected input value is not always the amount forfeited

The original design could consume the selected collateral input in full. CIP-40 introduces a collateral-return output and explicit accounting for the amount consumed. Its historical Alonzo restrictions should not be repeated as if later transaction formats had no return mechanism.

Current Cardano transaction API documentation exposes separate fields for collateral inputs, total collateral and return collateral. These fields describe different parts of the transaction. A wallet label showing a selected input of several ADA may therefore not be the same as its stated amount at risk.

Here is a fictional accounting example, not a current network minimum or fee quotation. A transaction selects a collateral input holding 5 ADA and specifies 0.3 ADA consumed with 4.7 ADA returned for the applicable failure path. The normal fee displayed for successful execution is 0.2 ADA. If that failure path is applied as specified, the collateral arithmetic is 5 minus 4.7 equals 0.3 ADA; do not assume the 5 ADA were all forfeited or add another 0.2 ADA without checking the actual result.

A return output must satisfy the applicable ledger conditions. CIP-40 also enables collateral inputs containing native assets when the return accounting preserves them; those assets do not become the ADA fee payment. A wallet may still impose a simpler ADA-only selection policy. Distinguish that product choice from a blanket statement that the protocol can never support assets in collateral inputs.

Review the failure-path recipient as well as the amount

The collateral mechanism documentation describes a return address for excess collateral after the Vasil upgrade. Check where that output sends value. A sensible amount with an unexpected recipient is not a correct transaction for your wallet, and a dApp's explanatory text does not replace the details of the request you sign.

For a hardware wallet or an interface that summarizes inputs, ask what it can actually verify. Do not assume a label called safe collateral proves that the wallet checked every input and output against the ledger. If the amount at risk or return destination is unclear, decline the request and obtain an explanation through the wallet or dApp's independently verified support channel.

How to investigate a claimed collateral charge

1. Save the network, transaction hash if one exists, full error and time. Distinguish the local attempt from a transaction actually found onchain.
2. Read the ledger result and identify the validation stage. Do not classify a phase-1 error as collateral consumption.
3. For an included failure, inspect the collateral inputs and the actual return output rather than only the normal recipient outputs.
4. Compare the consumed amount with the specified total collateral and applicable transaction format.
5. Check the receiving address of any collateral return in the correct wallet account and transaction history.
6. Separate other payments and later activity from the amount charged by this transaction. Provide support the public transaction evidence, not recovery credentials.

If no collateral-return output is present, do not invent one because a newer wallet usually creates it. Conversely, do not report an input's entire value as a loss when a real return output exists. Historical transaction evidence is more useful than a screenshot of the wallet's current total balance.

A retry is a new decision. Confirm that the intended payment was not completed, understand the failure and review the fresh transaction before authorizing it. Adding more collateral does not repair incorrect script logic or a missing signature. A request to disclose the seed to recover a collateral return is unrelated to the public ledger lookup.

For the native asset context, see the ADA page. Keep output minimums separate with the existing guide to minimum ADA for Cardano tokens. If you later use a no-account swap, follow that order's sending instructions; this script-collateral example does not establish that an exchange order requires a separate collateral transfer.