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

# Delta scans

> Refresh security coverage after code changes with delta Deep Scans.

Advanced Plan (Requires a plan that includes continuous coverage.)

A delta Deep Scan checks changed files and stale or unverified points on your [Attack surface map](https://docs.coderabbit.ai/security/attack-surface.md). It updates the existing map between full scans.

## Why use delta scans

Your code keeps changing after a Deep Scan, and each change makes part of your attack surface map out of date. A full Deep Scan refreshes everything, but it also rechecks code that has not changed.

A delta scan rechecks files changed since the latest complete full or delta scan, plus mapped points that are stale or were never verified.

* **Pay for the work done.** Cost depends on both changed files and stale or unverified points that need rechecking. The scan dialog shows the estimate before you run it.
* **Keep coverage current between full scans.** Findings in changed files are rechecked and the map is updated with the scan's results.
* **Scan when coverage drops.** With automation, CodeRabbit runs a delta only when verified coverage drops below your target. A regular full-scan schedule does not depend on coverage.

Run a full Deep Scan for broad repository changes or a fresh baseline.

## Before you begin

* Use CodeRabbit Cloud with a plan that includes continuous coverage.
* Start with a completed full Deep Scan of the repository from the last **30 days**. Your coverage must meet the minimum shown in the scan dialog.
* You need Security write access and access to the repository.

## Run a delta scan

**1. Open the scan dialog**

Go to **Security > Repositories**, select the repository, and choose **Run Deep Scan**.

**2. Choose a delta**

Select **Delta scan** or **Automate delta scans**. If you cannot select it, the dialog explains why.

**3. Run once**

Review the estimate and settings. Open the dropdown beside **Turn on automation** or **Save automation**, then select **Run delta now**.

## Automate delta scans

For GitHub repositories, open **Automate delta scans**, set **Keep verified coverage above** to your target, and select **Turn on automation**.

CodeRabbit checks coverage on a schedule. It also tries to check after changes merge into the default branch. If a merge check fails, the next scheduled check or a later merge can trigger a scan. A scan runs only when coverage is below your target and the scan and billing requirements are met.

To stop future checks, open **Manage automation** and turn it off.

> [!WARNING]
>
> Enabling automation replaces any existing full-scan schedule for this repository.

## Billing and results

You pay for the work the delta scan performs. To start a delta, your credits or monthly limit must cover the full-scan estimate. CodeRabbit returns whatever the delta does not use. A billing admin must approve paid runs. See [Security usage and limits](https://docs.coderabbit.ai/security.md#usage-and-limits).

Track results in **Security > Scan history**. A delta rechecks findings in the files it scans. If the baseline expires, coverage is too low, or more than **40% of the source files included by your scan settings** have changed, run a full Deep Scan.

## What's next

> **[Attack surface](https://docs.coderabbit.ai/security/attack-surface.md)**
>
> Understand verified coverage and stale points.

> **[Steer Deep Scans](https://docs.coderabbit.ai/security/steer-scans.md)**
>
> Configure source scope, context, and instructions.


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