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

# Self-trade prevention

> Orders from the same subaccount never fill against each other

Two orders from the same subaccount never fill against each other. The chain refuses a trade
between an account and itself, so the matcher does not try it.

## What happens

When your bid crosses your own ask in the same subaccount, the matcher skips that pair.

* **Neither order is cancelled.** Both stay on the book with no `cancel_reason`.
* **Both can still fill against other subaccounts.** The matcher moves on to the next crossed pair.

If your own order is the only one crossing yours, the book can show a crossed price until one of
them is cancelled or fills against someone else.

## Scope

Self-trade prevention compares **subaccounts**, not owners. Two subaccounts with the same owner can
trade with each other. If you run separate strategies from one wallet in separate subaccounts, they
can fill against each other.

To avoid crossing yourself, cancel your resting order before you submit one on the other side at
a crossing price.


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