Transaction Identification Number Mandatory Change

Fri 14 February 2014

Mandatory Change – Scheme Reference Data

The Card Schemes (Visa and MasterCard) have mandated that from 1st April 2014, a unique reference number must be flowed throughout the lifecycle of all card transactions. Visa refers to this data as the Transaction Identification Number, whilst MasterCard refers to it as the Trace Identification Number. Generically this data is referred to as Scheme Reference Data.

Visa and MasterCard have mandated these changes to allow for the accurate matching of authorisations to completed transactions, make the linking of chargebacks to their original transaction easier and allow representments to be traced back to the corresponding chargeback more easily. It will also aid in the prevention, research and detection of card fraud, making transactions more secure.

CityPay's Approach to the identification number

CityPay have always uniquely been referencing transactions. This is core to our infrastructure design and essential for correct functioning and referencing of transactional data. To fall in line with the mandate, this reference will be passed between ourselves and the acquiring bank using your merchant id and the transaction number using the an internal algorithm. Whilst this algorithm has been used for some time particularly for 3D secure processing (XID), it is being adapted from a 20 digit reference no to a 15 digit reference no.

This reference number is available on the Merchant Control Panel for each transaction.

This technical change is Acquirer specific with Acquirers such as First Data making this an internal change and not exposed through our integration. CityPay are currently working with Acquirers to ensure this change is in line with their requirements and specification.



This is currently with Development. The PayPOST API includes a new transactionId node to refer to this generated value which may be stored by your systems as appropriate. 

Paylink API

This is currently with Development. The Paylink API returns the transactionId as a new parameter in both post backs and return notifications.

PayPOS Card Present 

This is currently with Development. The PayPOS API returns the transactionId as part of its XML response document.



+44 (0)1534 884000