> ## Documentation Index
> Fetch the complete documentation index at: https://cts-docs.cosmos.network/llms.txt
> Use this file to discover all available pages before exploring further.

# Atomic Settlement

> Why settlement legs execute together or not at all, and what that removes.

Atomic settlement is the completion of every settlement leg, or none of them.
There is no state in which one side has moved and the other has not.

## The problem it removes

Settlement across two institutions has at least two legs: value leaves one party
and arrives at the other, and both sets of books have to record it.

Sequenced execution can fail between those legs. One side is debited and the
other is never credited, or value moves on chain and one party's ledger never
records it. Every mechanism built to survive that gap, whether a settlement
window, a reconciliation process, or a correspondent holding the balance in
between, exists because the gap exists.

Atomic execution removes the gap that other mechanisms manage.

## How it works on a shared ledger

Where both legs are recorded on the same ledger, they can execute in a single
transaction. The transaction either commits, in which case every leg is
recorded, or it fails, in which case none are.

On a settlement rail, the paying-side decrement and receiving-side credit are
one event. The books
balance by construction instead of by agreement.

The same property applies to an asset leg and a cash leg executed together. See
[Delivery vs Payment](/settlement/delivery-vs-payment).

## What it depends on

Atomicity is the all-or-nothing guarantee within a single ledger's transaction
boundary. Where settlement crosses two ledgers, the guarantee comes instead
from the messaging protocol: value is committed on the sending side, and a
verified acknowledgement confirms the receiving side acted. If the receiving
side rejects, or the message times out, the sending side reverses its
commitment.

That guarantee is not the same as single-transaction atomicity, and the
difference matters operationally. Cross-ledger settlement has an interval during
which the outcome is pending. Single-ledger settlement does not. See
[How IBC Works](/ibc/how-it-works) for the timeout and acknowledgement model.

<Note>
  This page is a placeholder for the operational detail. The atomic settlement
  combinations, behaviour when a cross-ledger leg times out, and operator surface
  for a pending settlement still need to be documented.
</Note>

## Related

* [How Settlement Works](/settlement/overview)
* [Settlement Options](/settlement/settlement-options)
* [Finality](/settlement/finality)