# Payment-CustomerId

The [customer](https://docs.monei.com/apis/rest/customers-create/) this payment belongs to. Linking a payment to a customer saves its payment method under that customer and groups the buyer's payments together.

Not to be confused with `paymentMethod.trustly.customerId`, which is an identifier Trustly returns for its own account holder and is unrelated.

**string**string\<uuid>

The [customer](https://docs.monei.com/apis/rest/customers-create/) this payment belongs to. Linking a payment to a customer saves its payment method under that customer and groups the buyer's payments together.

Not to be confused with `paymentMethod.trustly.customerId`, which is an identifier Trustly returns for its own account holder and is unrelated.

**Example:<!-- -->&#x20;**`a4e1d1dd-e0c2-4f7a-a2b1-2b0f1f9b6b1e`

Payment-CustomerId

```
"a4e1d1dd-e0c2-4f7a-a2b1-2b0f1f9b6b1e"
```