> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gr4vy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Payment account references

> A unique ID for the account behind the card

The Payment Account Reference (PAR) is a unique identifier assigned to the underlying account for which a card is used. This PAR
is generally the same for different cards tied to the same bank account. For example, the number on a physical card,
a virtual card for the same account, a network token, and an Apple or Google Pay token would all have the same PAR.

This also applies to updated cards that have changed the card number due to the card expiring or being lost.

## Use-cases

There are a few use cases for PARs.

1. Identifying fraud: Because the API does not return the original raw card number back via the API, it's hard to know if a card
   has been used previously in a fraudulent transaction. For example, two transactions with the same masked card number of
   `4111 11** **** 1111` could be the same number or two different numbers.
2. Identifying duplicate cards: Similarly, you could use the PAR to determine if the same card is stored twice for a user
   without needing to see the original number.

## Availability

The availability of a PAR depends on a few factors. Firstly, the payment service needs to return the PAR to the system. Secondly,
the connector needs to be implemented to pick up the PAR and return it back. When available, the `payment_account_reference` field
is returned as part of any `payment_method` on a [transaction](/reference/transactions/list-transactions), Please reach out to
support if the preferred connector does not yet have PAR enabled.

## Comparison to fingerprints

[Fingerprints](./fingerprints.mdx) and PARs go hand in hand to detect duplicate and fraudulent cards.

* PAR has limited availability and depends on the data received back from the payment service, while card fingerprints are available for every card transaction
* PARs represent the underlying account, while a fingerprint represents the actual card number. As a result, the fingerprint is different when using a digital wallet like Apple Pay or Google Pay.