Understanding Quantity-Based vs Amount-Based Matching

Last updated: March 11, 2026

OpenEnvoy uses intelligent matching strategies to align invoices with your purchase orders, regardless of how your company structures POs. While most invoices use quantity-based matching, certain PO types—such as blanket POs or invoice-level agreements—require amount-based matching instead.

This article explains the differences between these two matching approaches and how OpenEnvoy automatically determines which method to use.

Quantity-Based Matching (Default Method)

What it is

Quantity-based matching compares the physical quantities and unit prices on an invoice against what's available on the PO. This is the default method OpenEnvoy uses for most jobs.

When it's used

Quantity-based matching is ideal for:

  • Itemized material purchases

  • Manufacturing or component orders

  • Service POs with clearly defined deliverables on each line

How it works

With quantity-based matching:

  • The system matches at the individual invoice line level

  • When the PO can fully cover the invoice quantity, it draws down the full amount

  • If the PO cannot fully cover the quantity, the system draws down the maximum available and marks the job as "Invoice PO Pending"

This approach works best for POs that represent physical fulfillment of goods or services.

Amount-Based Matching (For Special PO Types)

What it is

Amount-based matching compares the total dollar amount of an invoice line against the PO—without requiring exact quantity or unit price alignment.

When it's used

Amount-based matching is designed for:

  • Blanket purchase orders with nominal unit prices (e.g., $1) and high quantities

  • Standing orders for recurring services or variable deliveries

  • Invoice-level PO lines where quantity is 1 and the amount matches the invoice total

  • Financial frameworks designed for long-term supplier relationships

Why it matters

In these scenarios, the quantity on the PO doesn't represent a physical deliverable—it's simply a placeholder for tracking authorized spend. Using quantity-based matching for these POs would create false mismatches and prevent invoices from processing correctly.

How OpenEnvoy Determines Which Method to Use

OpenEnvoy automatically detects when amount-based matching should apply using the following criteria:

1. Unit Price Detection The system recognizes when all PO lines have unit prices of $1 or other very low nominal values.

2. Blanket PO Patterns The system identifies POs with extremely high quantities and low unit prices typical of standing orders.

3. User-Applied Labels You can apply the AmountBasedPO label at the job or line level to force amount-based matching when needed.

4. ERP Indicators Data from your ERP may signal that a PO is structured for amount-based matching.

When the AmountBasedPO label is active, OpenEnvoy will automatically perform amount-based matching instead of quantity-based matching.

What Happens During Amount-Based Matching

When amount-based matching is used:

  • The matching logic focuses on line amount totals, not quantity or unit price

  • PO consumption is updated based on dollar amounts, not units

  • Invoice lines are tagged with AmountBasedPO

  • The sync to your ERP respects this designation to prevent false mismatches or rejections

This ensures that invoices using non-standard PO structures are matched accurately—without triggering unnecessary exceptions or blocking payment.

Need Help?

If you have questions about which matching method is being used for your jobs, or if you need to apply the AmountBasedPO label to specific vendors or PO types, please contact our support team.