Match rules - Lerian

Match rules define how Matcher compares transactions across sources. You can enforce strict matches, allow controlled variance, or model more advanced logic with composite conditions.

How rules work

When a matching run starts, Matcher evaluates rules in priority order.

Rules are evaluated from the lowest priority number to the highest.
The first rule that produces a match determines the outcome.
If no rule matches, the transaction becomes an exception.

This approach ensures deterministic matching while allowing progressively looser rules as fallbacks.

Rule types

Exact

Requires a strict match on the selected fields.

Best for: Deterministic matches where values should align 1:1.

Tolerance

Allows controlled variance (amount and/or date).

Best for: Known variance patterns such as fees, rounding, or posting delays.

Composite

Combines multiple conditions using AND/OR logic.

Best for: Scenarios that depend on multiple signals (amount, reference patterns, counterparties).

Exact rules

EXACT rules require the configured fields to match precisely.

Basic exact rule

cURL

curl -X POST "https://api.matcher.example.com/v1/contexts/ctx_abc123/rules" \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{
   "name": "Exact Amount and Date",
   "description": "Match when amount, currency, and date are identical",
   "type": "EXACT",
   "priority": 1,
   "conditions": {
     "fields": [
       "amount",
       "currency",
       "date"
     ]
   }
 }'

Response

{
  "id": "rule_001",
  "name": "Exact Amount and Date",
  "type": "EXACT",
  "priority": 1,
  "conditions": {
    "fields": [
      "amount",
      "currency",
      "date"
    ]
  },
  "status": "ACTIVE",
  "created_at": "2024-01-15T10:00:00Z"
}

Exact rule with reference matching

Match on external reference values, optionally constrained by a pattern:

{
  "name": "Exact Reference Match",
  "type": "EXACT",
  "priority": 1,
  "conditions": {
    "fields": [
      "reference",
      "currency"
    ],
    "reference_pattern": "^INV-\\d+$"
  }
}

This rule matches when:

reference matches exactly
currency matches
reference also matches the configured pattern

Tolerance rules

Tolerance rules accept variance while keeping the match bounded and explainable.

Percentage tolerance

cURL

curl -X POST "https://api.matcher.example.com/v1/contexts/ctx_abc123/rules" \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{
   "name": "1% Amount Tolerance",
   "description": "Match when amounts are within 1% and dates within 3 days",
   "type": "TOLERANCE",
   "priority": 2,
   "conditions": {
     "amount": {
       "tolerance_type": "percentage",
       "tolerance_value": 1.0
     },
     "date": {
       "tolerance_days": 3
     },
     "currency": {
       "must_match": true
     }
   }
 }'

Response

{
  "id": "rule_002",
  "name": "1% Amount Tolerance",
  "type": "TOLERANCE",
  "priority": 2,
  "conditions": {
    "amount": {
      "tolerance_type": "percentage",
      "tolerance_value": 1.0
    },
    "date": {
      "tolerance_days": 3
    },
    "currency": {
      "must_match": true
    }
  },
  "status": "ACTIVE"
}

Example:

Transaction A: $1,000.00 on 2024-01-15
Transaction B: $1,008.00 on 2024-01-17
Variance: 0.8% amount, 2 days → Matches

Absolute tolerance

Use fixed variance for scenarios like fees:

{
  "name": "Fixed $5 Tolerance",
  "type": "TOLERANCE",
  "priority": 3,
  "conditions": {
    "amount": {
      "tolerance_type": "absolute",
      "tolerance_value": 5.0
    },
    "date": {
      "tolerance_days": 1
    },
    "currency": {
      "must_match": true
    }
  }
}

Combined tolerance

Use both percentage and absolute tolerances (whichever is greater):

{
  "name": "Combined Tolerance",
  "type": "TOLERANCE",
  "priority": 4,
  "conditions": {
    "amount": {
      "tolerance_type": "combined",
      "percentage": 0.5,
      "absolute": 10.0
    }
  }
}

This matches when variance stays within 0.5% or $10.00 (whichever allows more headroom).

Composite rules

Composite rules let you express matching logic as a decision tree using AND/OR blocks.

And conditions

All conditions must pass:

cURL

curl -X POST "https://api.matcher.example.com/v1/contexts/ctx_abc123/rules" \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{
   "name": "Wire Transfer Matching",
   "type": "COMPOSITE",
   "priority": 2,
   "conditions": {
     "operator": "AND",
     "rules": [
       {
         "field": "amount",
         "tolerance_type": "percentage",
         "tolerance_value": 0.5
       },
       {
         "field": "reference",
         "match_type": "contains",
         "value": "WIRE"
       },
       {
         "field": "date",
         "tolerance_days": 5
       }
     ]
   }
 }'

Response

{
  "id": "rule_003",
  "name": "Wire Transfer Matching",
  "type": "COMPOSITE",
  "priority": 2,
  "conditions": {
    "operator": "AND",
    "rules": [
      {
        "field": "amount",
        "tolerance_type": "percentage",
        "tolerance_value": 0.5
      },
      {
        "field": "reference",
        "match_type": "contains",
        "value": "WIRE"
      },
      {
        "field": "date",
        "tolerance_days": 5
      }
    ]
  },
  "status": "ACTIVE"
}

Or conditions

At least one sub-condition must match:

{
  "name": "Flexible Reference Match",
  "type": "COMPOSITE",
  "priority": 5,
  "conditions": {
    "operator": "AND",
    "rules": [
      {
        "field": "amount",
        "match_type": "exact"
      },
      {
        "operator": "OR",
        "rules": [
          {
            "field": "reference",
            "match_type": "exact"
          },
          {
            "field": "external_id",
            "match_type": "exact"
          },
          {
            "field": "counterparty",
            "match_type": "exact"
          }
        ]
      }
    ]
  }
}

This matches when amount is exact AND one of reference, external_id, or counterparty matches.

Rule priority

Rules are evaluated by priority. Lower numbers run first.

Priority strategy

Priority	Rule type	Use case
1–10	EXACT	Deterministic matches
11–50	TOLERANCE (tight)	Small, expected variance
51–90	TOLERANCE (loose)	Broader variance that typically requires review
91–100	Catch-all	Last resort (use carefully)

Example priority configuration

[
  {
    "priority": 1,
    "name": "Exact Match",
    "type": "EXACT"
  },
  {
    "priority": 10,
    "name": "Reference Match",
    "type": "EXACT",
    "conditions": {
      "fields": [
        "reference"
      ]
    }
  },
  {
    "priority": 20,
    "name": "0.1% Tolerance",
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "tolerance_type": "percentage",
        "tolerance_value": 0.1
      }
    }
  },
  {
    "priority": 50,
    "name": "1% Tolerance",
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "tolerance_type": "percentage",
        "tolerance_value": 1.0
      }
    }
  },
  {
    "priority": 80,
    "name": "5% Tolerance",
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "tolerance_type": "percentage",
        "tolerance_value": 5.0
      }
    }
  }
]

Confidence scoring

Rules can contribute to confidence scoring so your run output reflects match quality, not just pass/fail.

{
  "name": "Amount Tolerance Rule",
  "type": "TOLERANCE",
  "priority": 20,
  "conditions": {
    "amount": {
      "tolerance_type": "percentage",
      "tolerance_value": 1.0
    }
  },
  "scoring": {
    "base_score": 80,
    "deductions": {
      "per_percent_variance": 5,
      "per_day_variance": 2
    }
  }
}

Example calculation:

Base score: 80
Amount variance 0.5%: -2.5 points
Date variance 2 days: -4 points
Final score: 73.5

Rule parameters reference

Amount conditions

Parameter	Type	Description
`tolerance_type`	String	`percentage`, `absolute`, or `combined`
`tolerance_value`	Decimal	Tolerance value
`percentage`	Decimal	Percentage for combined type
`absolute`	Decimal	Absolute value for combined type
`sign_agnostic`	Boolean	Ignore sign differences

Date conditions

Parameter	Type	Description
`tolerance_days`	Integer	Days before and after
`days_before`	Integer	Days before only
`days_after`	Integer	Days after only
`use_posting_date`	Boolean	Use posting date instead of transaction date

String conditions

Parameter	Type	Description
`match_type`	String	`exact`, `contains`, `starts_with`, `ends_with`, `regex`
`case_sensitive`	Boolean	Case-sensitive matching
`value`	String	Value or pattern to match

Practical examples

Bank reconciliation rules

[
  {
    "name": "Exact Match - Same Day",
    "priority": 1,
    "type": "EXACT",
    "conditions": {
      "fields": [
        "amount",
        "currency",
        "date"
      ]
    },
    "scoring": {
      "base_score": 100
    }
  },
  {
    "name": "Exact Amount - Date Lag",
    "priority": 10,
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "match_type": "exact"
      },
      "date": {
        "tolerance_days": 3
      },
      "currency": {
        "must_match": true
      }
    },
    "scoring": {
      "base_score": 95,
      "deductions": {
        "per_day_variance": 1
      }
    }
  },
  {
    "name": "Bank Fee Tolerance",
    "priority": 20,
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "tolerance_type": "absolute",
        "tolerance_value": 50.0
      },
      "date": {
        "tolerance_days": 3
      },
      "currency": {
        "must_match": true
      }
    },
    "scoring": {
      "base_score": 85
    }
  }
]

Payment gateway reconciliation

[
  {
    "name": "Payment ID Match",
    "priority": 1,
    "type": "EXACT",
    "conditions": {
      "fields": [
        "external_id",
        "amount",
        "currency"
      ]
    },
    "scoring": {
      "base_score": 100
    }
  },
  {
    "name": "Processing Fee Tolerance",
    "priority": 15,
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "tolerance_type": "percentage",
        "tolerance_value": 3.0
      },
      "date": {
        "tolerance_days": 2
      },
      "currency": {
        "must_match": true
      }
    },
    "description": "Allow up to 3% for payment processing fees",
    "scoring": {
      "base_score": 90
    }
  }
]

Intercompany reconciliation

[
  {
    "name": "Exact Intercompany Match",
    "priority": 1,
    "type": "EXACT",
    "conditions": {
      "fields": [
        "amount",
        "currency",
        "reference"
      ]
    },
    "scoring": {
      "base_score": 100
    }
  },
  {
    "name": "FX Variance Tolerance",
    "priority": 20,
    "type": "TOLERANCE",
    "conditions": {
      "amount": {
        "tolerance_type": "percentage",
        "tolerance_value": 2.0
      },
      "currency": {
        "must_match": false
      },
      "date": {
        "tolerance_days": 5
      }
    },
    "description": "Allow FX conversion variance",
    "scoring": {
      "base_score": 85
    }
  }
]

Testing rules

Test rules in dry-run mode before applying changes to production contexts.

Dry run a matching job

cURL

curl -X POST "https://api.matcher.example.com/v1/contexts/ctx_abc123/match" \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{
   "mode": "dry_run",
   "date_from": "2024-01-01",
   "date_to": "2024-01-31"
 }'

Response

{
  "job_id": "job_dry_001",
  "mode": "dry_run",
  "status": "COMPLETED",
  "summary": {
    "transactions_analyzed": 1000,
    "potential_matches": 920,
    "potential_exceptions": 80,
    "by_rule": [
      {
        "rule_id": "rule_001",
        "rule_name": "Exact Match",
        "matches": 750
      },
      {
        "rule_id": "rule_002",
        "rule_name": "1% Tolerance",
        "matches": 150
      },
      {
        "rule_id": "rule_003",
        "rule_name": "5% Tolerance",
        "matches": 20
      }
    ]
  },
  "note": "Dry run - no changes applied"
}

Test a specific rule

curl -X POST "https://api.matcher.example.com/v1/rules/rule_002/test" \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{
   "transactions": [
     {
       "id": "txn_1",
       "amount": 1000.0,
       "currency": "USD",
       "date": "2024-01-15"
     },
     {
       "id": "txn_2",
       "amount": 1005.0,
       "currency": "USD",
       "date": "2024-01-16"
     }
   ]
 }'

Response

{
  "rule_id": "rule_002",
  "would_match": true,
  "confidence": 92,
  "details": {
    "amount_variance": 0.5,
    "amount_variance_percent": 0.5,
    "date_variance_days": 1
  }
}

Managing rules

List rules

curl -X GET "https://api.matcher.example.com/v1/contexts/ctx_abc123/rules" \
 -H "Authorization: Bearer $TOKEN"

Update rule priority

curl -X PATCH "https://api.matcher.example.com/v1/rules/rule_002" \
 -H "Authorization: Bearer $TOKEN" \
 -H "Content-Type: application/json" \
 -d '{
   "priority": 15
 }'

Disable a rule

curl -X POST "https://api.matcher.example.com/v1/rules/rule_002/disable" \
 -H "Authorization: Bearer $TOKEN"

Delete a rule

curl -X DELETE "https://api.matcher.example.com/v1/rules/rule_002" \
 -H "Authorization: Bearer $TOKEN"

Best practices

Start strict, then loosen

Lead with exact rules. Add tolerance rules only for the variance you can justify and explain.

Leave room in priorities

Use gaps (1, 10, 20, 50) so you can insert rules without renumbering your entire set.

Dry-run every change

Treat rule updates as production changes. Validate match rates and exception volume before committing.

Write descriptions that explain intent

A rule should document the variance it covers and the risk it introduces.

Review rule output over time

If a rule never matches, it may be unnecessary. If it matches too often, it may be too broad.

Keep loose rules at low priority

High tolerance increases false positives. Use it as a fallback and review results carefully.

Next steps

Exception routing

Configure classification, assignment, and escalation for unmatched transactions.

Confidence scoring

Understand how scores are calculated and how thresholds impact automation.

Introduction

Getting started

Configuration

Daily reconciliation

Integrations

Reference

​How rules work

​Rule types

​Exact

​Tolerance

​Composite

​Exact rules

​Basic exact rule

​Response

​Exact rule with reference matching

​Tolerance rules

​Percentage tolerance

​Response

​Absolute tolerance

​Combined tolerance

​Composite rules

​And conditions

​Response

​Or conditions

​Rule priority

​Priority strategy

​Example priority configuration

​Confidence scoring

​Rule parameters reference

​Amount conditions

​Date conditions

​String conditions

​Practical examples

​Bank reconciliation rules

​Payment gateway reconciliation

​Intercompany reconciliation

​Testing rules

​Dry run a matching job

​Response

​Test a specific rule

​Response

​Managing rules

​List rules

​Update rule priority

​Disable a rule

​Delete a rule

​Best practices

​Next steps

Exception routing

Confidence scoring

How rules work

Rule types

Exact

Tolerance

Composite

Exact rules

Basic exact rule

Response

Exact rule with reference matching

Tolerance rules

Percentage tolerance

Response

Absolute tolerance

Combined tolerance

Composite rules

And conditions

Response

Or conditions

Rule priority

Priority strategy

Example priority configuration

Confidence scoring

Rule parameters reference

Amount conditions

Date conditions

String conditions

Practical examples

Bank reconciliation rules

Payment gateway reconciliation

Intercompany reconciliation

Testing rules

Dry run a matching job

Response

Test a specific rule

Response

Managing rules

List rules

Update rule priority

Disable a rule

Delete a rule

Best practices

Next steps