# Buyer

Source: https://developer.avalara.com/products/excise/integration-guides/excise/ubn3358147965504/

Guide: AvaTax Excise

# Buyer

Details about the `Buyer` field in the RestTransaction model and its usage in transactions.

**Element type**: Required

**Endpoints/models used**: [RestTransaction](https://developer.avalara.com/api-reference/excise/v1/models/Avalara.Excise.Determination.Engine.RestTransaction/)

Each transaction must identify who is purchasing the goods. This is done using the `Buyer` field in the [RestTransaction](https://developer.avalara.com/api-reference/excise/v1/models/Avalara.Excise.Determination.Engine.RestTransaction/) model. This field should match the [Custom ID](https://developer.avalara.com/excise/business-entities/custom-id) of the buyer in the ATE business entities table.

## Example

```
{
    "EffectiveDate": "2024-09-01",
    "InvoiceDate": "2024-09-01",
    "InvoiceNumber": "CertTest_5",
    "FuelUseCode": "",
    "TitleTransferCode": "DEST",
    "TransactionType": "ABOVE",
    "TransportationModeCode": "R",
    "Buyer": "SUPPLIER2",
    "Seller": "SUPPLIER1",
    "UserData": "ATE_POSTMAN",
    "UserTranId": "CertTest_5",
    "SourceSystem": "POSTMAN",
    "CustomString1": "Certification",
    "CustomString2": "Test",
    "CustomString3": "No_1_167",
    "CustomString4": "",
    "CustomString5": "",
    "CustomString6": "",
    "CustomString7": "",
    "CustomString8": "",
    "CustomString9": "",
    "CustomString10": "",
    "CustomNumeric1": 0,
    "CustomNumeric2": 0,
    "CustomNumeric3": 0,
    "CustomNumeric4": 0,
    "CustomNumeric5": 0,
    "CustomNumeric6": 0,
    "CustomNumeric7": 0,
    "CustomNumeric8": 0,
    "CustomNumeric9": 0,
    "CustomNumeric10": 0,
    "AvataxTransactionType": "SalesInvoice",
    "Discount": "0.00",
    "EntityUseCode": ""
    "TransactionLines": [
        {
            ...
        }
    ]
}
```