# Sale Rate Changes during Billing
**YouTube:** [How to Enable Sale Rate Changes during billing?](https://www.youtube.com/watch?v=JqxlDBtaddM)
## How to Enable Sale Rate Changes during billing?
In this tutorial, we’ll guide you through the process of enabling and changing the **sale rate at runtime during billing** in Logic ERP.
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### Attempt to Change the Sale Rate
* Start by generating a **Sales Bill**.
* Try to edit the **Sale Rate** during billing.
* You’ll notice that the software does **not allow rate modification** because the **Rate column is locked** by default for security reasons.
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### Unlock the Rate Column
To enable rate changes at the time of billing:
* Go to **Sale Voucher Configuration**.
* Select the **Relevant Billing Series**.
* Open the **Column Locks** section.
* Locate and **Unlock the Rate Column**.
* Save the configuration changes.
Unlocking the column allows authorized users to modify the sale rate during billing.
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### Modify the Rate During Billing
* Return to the **Billing Screen**.
* Start creating a **New Sales Bill**.
* Edit the **Sale Rate** directly in the bill.
* The software will now accept the updated rate for this transaction.
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### Understand the Scope of Rate Modification
* The **modified rate applies only to the current bill**.
* When you generate the **next bill for the same item**, the software automatically applies the **original lot rate**.
* This ensures that any changes made during billing do **not affect future bills** or the base item configuration.
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### Save and Verify
* Save the **Current Bill** with the modified rate.
* Create a **New Bill** for the same item to verify that the system reverts to the original lot rate.
This confirms that runtime rate changes are limited to individual transactions, maintaining the integrity of your pricing setup.
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### Key Takeaways
* **Column Locks** in Logic ERP control whether sale rates can be edited during billing.
* Unlocking the rate column provides flexibility for specific cases without altering the default item rates.
* Changes made at runtime affect only the **current bill** and do not impact future transactions.
