---
title: Configure Quantity Proration for Product Updates
url: https://docs.maxio.com/billing/subscriptions/management/product-allocations/configure-quantity-proration-for-product-updates
applies_to: Advanced Billing
updated: 2026-10-21
---

# Configure Quantity Proration for Product Updates

Updating a Product quantity in Advanced Billing affects how charges appear on an Invoice. It's important to understand how **Update Quantity** differs from **Record Usage**, especially when working with quantity-based and metered Products.

> **Important:** To charge a Customer for a Product, you must report the Product's quantity or usage to Advanced Billing. See <a href="https://docs.maxio.com/billing/subscriptions/management/product-allocations/understand-how-products-are-billed" target="_blank" rel="noopener noreferrer">Understand How Products Are Billed</a> for how Product Allocations work.

> Each Advanced Billing Site defaults the upgrade proration setting to **Prorate and Accrue**.

## Update Quantity vs. Record Usage

The action you use depends on the Product type:

- **Update Quantity** applies to quantity-based Products.
- **Record Usage** applies only to metered Products.
- Metered Products reset to zero at the beginning of each billing period.

![Component allocation form with the quantity, the price point, and the proration choices for a price increase, a charge, a failed payment and a price decrease](https://docs.maxio.com/content-images/billing/subscriptions/management/product-allocations/configure-quantity-proration-for-product-updates/24251887708301_quantity_options.png)

*Example of updating a quantity-based Product*

## Update quantity and proration

When you update the quantity of a quantity-based Product using the **Update Quantity** action, you can choose to charge a prorated amount by selecting the **Charge the prorated amount of the difference in quantity** option.

![Charge the prorated amount option](https://docs.maxio.com/content-images/billing/subscriptions/management/product-allocations/configure-quantity-proration-for-product-updates/24251888501261_co_UpdateQuantity_ChargeProratedDifferenceQuantity.png)

*The Charge the prorated amount of the difference in quantity option*

The following formula applies when proration is enabled:

`Delta Quantity × Price × % of Period`

*Where:*

- `Delta Quantity` = New Quantity − Old Quantity
- `% of Period` = (Current Timestamp − Start of Period) ÷ Original Period Length

### How proration appears on the Invoice

On the Invoice:

- Quantity = `Delta Quantity × % of Period`
- Unit Price = `Price`

### Proration example

*Given:*

- The Update Quantity action changes the quantity from 20 to 25.
- The change occurs 49.9% into the billing period.
- The price per unit is $20.

*Result:*

The Invoice displays:

- Quantity = 2.495 (5 × 49.9%)
- Unit Price = $20
- Total = $49.90 ($20 × 2.495)

![Invoice example showing prorated quantity](https://docs.maxio.com/content-images/billing/subscriptions/management/product-allocations/configure-quantity-proration-for-product-updates/24251873198989_ex_UpdateQuantity.png)

*The prorated quantity on the Invoice*

## Display prorated price instead of prorated quantity

By default, proration adjusts the quantity on the Invoice Line Item.

**To display a prorated Unit Price instead**

1. Navigate to **Config > Settings > Invoices**.
2. Under **Invoice Customization > Line Items and Billing**, select **Display Prorated Price Invoice Lines**.

![Display of Prorated Price Invoice Lines setting](https://docs.maxio.com/content-images/billing/subscriptions/management/product-allocations/configure-quantity-proration-for-product-updates/24251904373645_co_UpdateQuantity_DisplayProratedPriceInvoiceLines.png)

*The Display Prorated Price Invoice Lines setting*

When this setting is enabled, the proration percentage applies to the **Unit Price** instead of the quantity.

- Quantity = `Delta Quantity`
- Unit Price = `Price × % of Period`

Using the same example:

- Quantity = 5 (25 − 20)
- Unit Price = $9.98 ($20 × 49.9%)
- Total = $49.90 (5 × $9.98)

In both scenarios, the total charge on the Invoice is $49.90. Only the presentation of the Invoice Line Item differs.