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

# Matching Rules

> Determine how Blnk compares and matches records between your Ledger and external data.

***

## Overview

Matching rules are used by Blnk to determine how to compare and match your ledger records with your external records. These rules define how fields like amount, date, and reference are compared, with flexibility for small discrepancies (called drifts).

In this guide, you'll learn how to set matching rules and apply them when running reconciliation.

***

## Creating a matching rule

To create a new matching rule, call the [Create matching rule](/reference/create-matching-rule) endpoint:

```
POST https://YOUR_BLNK_INSTANCE_URL/reconciliation/matching-rules
```

```json Sample request theme={"system"}
{
    "name": "Default matcher",
    "description": "Amount with 1% drift matcher",
    "criteria": [
        {
            "field": "amount",
            "operator": "equals",
            "allowable_drift": 0.01
        },
        {
            "field": "currency",
            "operator": "equals"
        },
        {
            "field": "date",
            "operator": "equals",
            "allowable_drift": 1800
        },
        {
            "field": "reference",
            "operator": "contains"
        }
    ]
}
```

***

## Editing and deleting matching rules

After creating a matching rule, you can update it or remove it when it's no longer needed:

* **Update:** Use the [Update matching rule](/reference/update-matching-rule) endpoint to change the name, description, or criteria of an existing rule.
* **Delete:** Use the [Delete matching rule](/reference/delete-matching-rule) endpoint to remove a rule from your reconciliation workflows.

***

## How Blnk matches transactions during reconciliation

Blnk ensures accurate reconciliation by comparing external records with your ledger records based on five key attributes:

| Attributes    | Operators                             | What it does                                                          |
| :------------ | :------------------------------------ | :-------------------------------------------------------------------- |
| `amount`      | `equals`, `greater_than`, `less_than` | Compares transaction amounts.                                         |
| `currency`    | `equals`                              | Ensures both transactions use the same currency.                      |
| `date`        | `equals`, `after`, `before`           | Matches transactions based on their timestamps.                       |
| `reference`   | `equals`, `contains`                  | Checks if the transaction reference matches or is partially included. |
| `description` | `equals`, `contains`                  | Matches transactions based on their descriptions.                     |

***

## Understanding matching operators

Each attribute is matched using specific operators, which determine how strict the comparison is:

| Operators      | Description                                                  |
| :------------- | :----------------------------------------------------------- |
| `equals`       | Both records must match exactly.                             |
| `contains`     | Parts of the external record match the internal record.      |
| `greater_than` | The external amount must be higher than the internal amount. |
| `less_than`    | The external amount must be lower than the internal amount.  |
| `after`        | The external date must be later than the internal date.      |
| `before`       | The external date must be earlier than the internal date.    |

### Example scenarios

Here's how these rules work during reconciliation:

<Steps>
  <Step title="Matching amounts">
    | External amount | Internal amount | Operator used  | Match? |
    | :-------------- | :-------------- | :------------- | :----- |
    | \$100.00        | \$100.00        | `equals`       | ✅ Yes  |
    | \$105.00        | \$100.00        | `greater_than` | ✅ Yes  |
    | \$95.00         | \$100.00        | `greater_than` | ❌ No   |
  </Step>

  <Step title="Matching dates">
    | External date  | Internal date  | Operator used | Match? |
    | :------------- | :------------- | :------------ | :----- |
    | March 10, 2025 | March 10, 2025 | `equals`      | ✅ Yes  |
    | March 12, 2025 | March 11, 2025 | `after`       | ✅ Yes  |
    | March 10, 2025 | March 11, 2025 | `after`       | ❌ No   |
  </Step>

  <Step title="Matching references">
    | External amount | Internal amount | Operator used | Match? |
    | :-------------- | :-------------- | :------------ | :----- |
    | "REF-12345"     | "12345"         | `contains`    | ✅ Yes  |
    | "INV-56789"     | "INV-56789"     | `equals`      | ✅ Yes  |
    | "12345"         | "REF-12345"     | `contains`    | ❌ No   |
  </Step>
</Steps>

### Why this matters

1. **Flexibility:** Use operators like `contains`, `greater_than`, and `before` to account for processing delays, fees, and partial matches.

2. **Precision:** Ensure transactions are matched accurately, reducing errors in reconciliation.

3. **Control:** Customize your matching rules to fit your financial workflows.

***

## Handling discrepancies with drifts

Small differences in amounts or dates—like fees or time zone shifts—can disrupt reconciliation.

The `allowable_drift` field sets a tolerance range for matches, used with the `equals` operator. Blnk supports two types:

1. **Amount drift:** Tolerates value differences (e.g., 0.01 = 1% drift).

   <Note>A \$100 internal record with 1% drift matches \$99 – \$101 external records.</Note>

2. **Date drift:** Allows for time differences (e.g., 3600 = 1 hour).

   <Note>A 2:00 PM internal record with 1-hour drift matches 1:00–3:00 PM external timestamps.</Note>

### When to use drifts

1. Use amount drift when:
   * Your external data includes processing fees or minor exchange rate variations.
   * Your system rounds transactions differently from external sources.

2. Use date drift when:
   * Your transactions involve cross-time-zone processing.
   * Payment settlements take hours or days to finalize.

***

## Best practices

To ensure accurate and reliable financial reconciliation, follow these best practices when defining matching rules:

1. **Optimize for efficiency:** Reduce manual effort by implementing automated matching rules.

2. **Use Drifts Strategically:** Apply allowable drifts to handle small discrepancies without compromising accuracy.

3. **Ensure accuracy:** Minimize human errors with consistent and precise rule application.

4. **Design for scalability:** Use robust rules that can handle high transaction volumes and complex financial products.

5. **Maintain compliance:** Align matching rules with regulatory requirements for transparency.

6. **Regularly review & optimize:** Continuously assess and refine matching rules based on reconciliation performance and error patterns.

7. **Audit logs:** Maintain detailed logs of matching decisions to support audits and troubleshooting.

***

## Need help?

We are very happy to help you make the most of Blnk, regardless of whether it is your first time or you are switching from another tool.

To ask questions or discuss issues, please [contact us](mailto:support@blnkfinance.com) or [join our Discord community](https://discord.gg/7WNv94zPpx).

***

<Tip>
  **Tip:** Connect to Blnk Cloud to see your Core data.

  You can view your transactions, manage identities, create custom reports, invite other team members to collaborate, and perform operations on your Core — all in one dashboard.

  [Check out Blnk Cloud →](https://www.blnkfinance.com/products/cloud)
</Tip>