UUIDs in Spend & Expense API

BILL is introducing UUIDs in the Spend & Expense API. Each ID value that uniquely identifies an entity in Spend & Expense (such as a budget, transaction, or user) now follows the UUID4 format.

UUID v4 (or UUID4) is a randomly-generated 128-bit identifier and is highly secure. The introduction of UUIDs in the Spend & Expense API is another measure taken by BILL for further improving its security standards.

Spend & Expense webhook notifications

When BILL sends notifications for the spend.transactions.updated event, each ID in the notification payload is a UUID value. For example, uuid is the UUID of the transaction, and userUuid is the UUID of the user that created the transaction.

See Spend & Expense transaction notification payloads for more information.

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IMPORTANT

While the spend.transactions.updated notification payload includes only uuid values and no id values, the Spend & Expense API responses continue to present both uuid and id values.

In the future, the Spend & Expense id values will deprecated. We will share more information when we have a timeline for this deprecation.

GET operations

Let's use the example of budgets to understand the impact of introducing UUIDs on the Spend & Expense GET operations.

When you get details about a budget with GET /v3/spend/budgets/{budgetId}, you currently set the budget id in your API request. Moving forward, you can set the budget uuid as another method for getting details about a budget.

GET response fields

For each existing Spend & Expense API object, BILL has generated a uuid value for each id value. In the GET /v3/spend/budgets/{budgetId} response example, both the uuid and id values are available to uniquely identify the budget.

Similarly, for fields with an id suffix, we now have the same field with the uuid suffix to present the UUID value. For example, for the parentBudgetId field in the API response for a budget, we now have a additional parentBudgetUuid field to present the UUID of the parent budget.

{
    "id": "QnVkZ2V0OjUyOTg2MQ==",
    "uuid": "bgt_mur9ttm5tt0m97tjj287s744t4",   // NEW UUID VALUE
    "name": "Happy Music Supplies monthly spending budget",
    "retired": false,
    "startDate": "2025-12-15",
    "recurringInterval": "MONTHLY",
    "timezone": "US/Eastern",
    "autoAddUsers": false,
    "receiptRequired": true,
    "carryOver": false,
    "budgetGroup": false,
    "parentBudgetId": "{parent_budget_id}",
    "parentBudgetUuid": "{parent_budget_uuid}",   // NEW UUID VALUE
    "shareFunds": "SHARE_MANUALLY",
    "recurringLimit": 200.00,
    "limitlessOverspend": false,
    "currentPeriod": {
        "startDate": "2025-12-01",
        "endDate": "2026-01-01",
        "limit": 200.00,
        "overspendBuffer": 0.00,
        "assigned": 0.00,
        "spent": {
            "cleared": 0.00,
            "pending": 0.00,
            "total": 0.00
        }
    },
    "default": false
}

POST, PATCH, PUT, and DELETE operations

Currently, you cannot use UUID values in the Spend & Expense POST, PATCH, PUT or DELETE operations. This feature will be available in the future. We will share more information when this feature is available.