---
title: "Adding system properties to transactions and to transaction types"
slug: "adding-system-properties-to-transactions-and-to-transaction-types"
updated: 2026-02-05T12:46:19Z
published: 2026-02-05T12:46:19Z
canonical: "support.lusid.com/adding-system-properties-to-transactions-and-to-transaction-types"
---

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

# Adding system properties to transactions and to transaction types

A [system property](/v1/docs/what-is-a-system-property) is a built-in function that is either read-only or writable.

> **Note**: You interact with a system property (that is, add, update and retrieve it) in the same way as a [custom property](/v1/docs/how-do-i-add-a-property-to-an-entity). A system property has a 3-stage key that is either in the protected `system` or `default` scope.

## Adding system properties to individual transactions

You can add any of the [writable system properties in this table](/v1/docs/what-is-a-system-property#transaction-system-properties) to a transaction and specify a value that LUSID can then use in a business operation.

Consider the following example of a call to the [BatchUpsertTransactions](https://www.lusid.com/docs/api#operation/BatchUpsertTransactions) API to upsert a foreign currency transaction, where:

- The `TradeToPortfolioRate` system property specifies an exchange rate for the transaction currency to the portfolio currency, enabling LUSID to maintain the cost basis of the portfolio.
- The `TaxLotSelectionMethod` system property overrides the default accounting method, set either on the transaction type (see below) or on the portfolio.

```json
curl -X POST 'https://<your-domain>.lusid.com/api/api/transactionportfolios/Finbourne-Examples/Global-Equities/transactions/$batchUpsert?successMode=Partial' 
  -H 'Content-Type: application/json-patch+json'
  -H 'Authorization: Bearer <your-API-access-token>'
  -d '{
  "transactionRequest-1": {
    "transactionId": "Txn-0000001",
    "type": "Buy",
    "instrumentIdentifiers": {
      "Instrument/default/Figi": "BBG000C6K6G9",
    },
    "transactionDate": "2023-05-15T00:00:00.0000000+00:00",
    "settlementDate": "2023-05-18T00:00:00.0000000+00:00",
    "units": 1000,
    "transactionPrice": {
      "price": 120, "type": "Price"
    },
    "totalConsideration": {
      "amount": 120000, "currency": "GBP"
    },
    "properties": {
      "Transaction/default/TradeToPortfolioRate": {
        "key": "Transaction/default/TradeToPortfolioRate",
        "value": {
          "metricValue": {
            "value": 0.93,
            "unit": ""
          }
        }
      },
      "Transaction/default/TaxLotSelectionMethod": {
        "key": "Transaction/default/TaxLotSelectionMethod",
        "value": {
          "labelValue": "LowestCostFirst"
        }
      }
    }
  }
}'
```

## Adding system properties to transaction types

You can add any of the [system properties in this table](/v1/docs/what-is-a-system-property#transaction-type-system-properties) to a [transaction type](/v1/docs/what-is-a-transaction-type) to change the default behavior for all the transactions belonging to that type.

> **Note**: Some system properties are set on the transaction type itself, and some on an individual movement within the transaction type.

Consider the following example of a call to the [SetTransactionType](https://www.lusid.com/docs/api#operation/SetTransactionType) API to create a custom `BuyProRated` transaction type, where:

- The `TaxLotSelectionMethod` system property (specified on the first movement) overrides the default accounting method, set on the portfolio.
- The `AllocationMethod` system property (set on the transaction type itself) is set to `Prorated` to automatically split transactions that do not themselves have an SHK across all SHKs defined for the portfolio.

```json
curl -X POST 'https://<your-domain>.lusid.com/api/api/transactionconfiguration/types/Bloomberg/BuyProRated?scope=default' 
  -H 'Content-Type: application/json-patch+json'
  -H 'Authorization: Bearer <your-API-access-token>'
  -d '{
   "aliases": [
     {
       "type": "BuyProRated",
       "description": "A custom transaction type to automatically split transactions across sub-holdings",
       "transactionClass": "Buy",
       "transactionRoles": "Longer",
       "isDefault": false
     },
   ],
   "movements": [
     {
       "movementTypes": "StockMovement",
       "side": "Side1",
       "direction": 1,
       "properties": {
         "TransactionConfiguration/default/TaxLotSelectionMethod": {
           "key": "TransactionConfiguration/default/TaxLotSelectionMethod",
           "value": {
             "labelValue": "LastInFirstOut"
           }
         }
       },
       "mappings": [],
       "movementOptions": []
     },
     {
       "movementTypes": "CashCommitment",
       "side": "Side2",
       "direction": -1,
       "properties": {},
       "mappings": [],
       "movementOptions": []
     }
   ],
   "properties": {
     "TransactionConfiguration/default/AllocationMethod": {
       "key": "TransactionConfiguration/default/AllocationMethod",
       "value": {
         "labelValue": "Prorated"
       }
     }
   }
  }'
```