# MESSAGE acmt.023 Identification Verification Request

The `acmt.023` message is used for:

* (a) **proxy resolution requests** and
* (b) **account resolution requests.**

The messages for both use cases are very similar, with only slightly different information being provided.

For further detail on each element in the `acmt.023` and `acmt.024`, please refer to the [Message Guidelines (Excel)](/messaging-and-translation/message-guidelines-excel.md).

## Structure of the acmt.023 Identification Verification Request V03 <a href="#toc143525634" id="toc143525634"></a>

<figure><img src="/files/LHGt8h8oEhWKuSwsuFnV" alt=""><figcaption><p>Main blocks of the acmt.023 Identification Verification Request V03</p></figcaption></figure>

The acmt.023 message has two main blocks:

* **Assignment** contains information about who is making the request and where that request should be sent:
  * **Creator** describes the Sender of the payment, who is initiating the proxy/account resolution request prior to sending a payment instruction
  * **First Agent** and **Assigner** both describe the Source PSP, acting on behalf of the Creator (Sender)
  * **Assignee** describes the entity that the request is assigned to. Depending on the local implementation, this will initially be set to the Source IPSO or Source Proxy Directory Operator (S-PDO).
  * The element *Assignee > Agent > PostalAddress > Country* **must** be set to the Destination Country as selected by the Sender. (This helps Nexus to route the request to the appropriate proxy directory.)
  * Nexus will update the Assignee to the relevant Destination Proxy Directory Operator or Creditor Agent
* **Verification** contains information about the proxy or account we are trying to verify
  * The ***PartyAndAccountIdentification >*** ***Account*** element contains one of the following:
    * An IBAN (*PartyAndAccountIdentification > Account > Identification > IBAN*)
    * An account ID (which must be accompanies by a Financial Institution Identifier in the Agent block) (*PartyAndAccountVerification > Account > Identification > Other > Identification*)
    * A ProxyId and ProxyType code (*PartyAndAccountIdentification > Account > Proxy > Identification and PartyAndAccountIdentification > Account > Proxy > Type > Code* )
  * In some cases (such as the Philippines) a proxy must be accompanied by the BIC of the financial institution in the Agent block. In this case, Nexus will include the BIC as one of the address inputs provided via the API call; the Source PSP does not need to implement custom logic for these cases).

{% hint style="info" %}
The ***PartyAndAccountIdentification > Party*** block would be used for a **Comparison** model of verification, in which the Debtor has provided information about the Recipient, which can be sent to the Destination PSP. The Destination PSP will compare that information to the actual information they have on record, and reply either with a code that describes the degree of match, or with corrected information (assuming the original information was close enough). **This model is not currently supported in Nexus**, but may be developed in future.
{% endhint %}

## Using acmt.023 for Proxy Resolution <a href="#toc143525635" id="toc143525635"></a>

* The proxy provided by the Sender should be included in the *Verification > PartyAndAccountIdentification > Account > Proxy* element:
* *Type* should include the ISO 20022 *ExternalProxyAccountType1Code* (eg *MBNO*) for the proxy type that was selected by the Sender. This code would have been provided by Nexus to the Source PSP when the Source PSP calls the GET /countries/{countryCode}/addressTypes option.
* *Identification* should include the actual proxy value, as text, as provided by the Sender (as entered into the Source PSP’s app)

{% hint style="info" %}
**Uniquely identifying the Debtor:** To allow the Proxy Directory Operator to guard against abuse (eg entering multiple phone numbers into a Nexus-enabled app in order to get the corresponding account holder names), the field *Assignment > Creator > Party* > *Identification > PrivateIdentification > Other > Identification* element **should** include a unique ID that uniquely identifies the Sender. To avoid sensitive data, this ID should ideally be a generated hash value that will be reused for all requests from this Sender. However, the Source PSP may instead provide an official ID (eg National Identity Number), an internal customer ID.

The PDO can (optionally) use this value to rate-limit the number of requests coming from a particular Sender. (This is recommended but not mandatory.)
{% endhint %}

#### Using acmt.023 for Account Resolution <a href="#toc143525636" id="toc143525636"></a>

* The Account Identifier provided by the Sender should be included in the *Verification > PartyAndAccountIdentification > Account* element
* IBANs are included in the *Account > Id > IBAN* element
* Non-IBAN Account Identifiers should be given in *the Account > Id > Other > Id* element
* The PSP / Financial Institution Identifier provided by the Sender should be included in the *Verification > PartyAndAccountInformation > Agent* section
  * If a BIC is used, it should be given in *Agent > FinancialInstitutionIdentification > BICFI* element
  * If a non-BIC Financial Institution Identifier is used,
    * The Financial Institution Identifier should be given in *Agent > ClearingSystemMemberIdentification > MemberIdentification* element
    * The *Agent > FinancialInstitutionIdentification > ClearingSystemMemberIdentification > ClearingSystemIdentification > Code* element should be filled with the IPSO’s ExternalClearingSystemIdentification1Code (from the ISO 20022 External Code Set)

{% hint style="info" %}
IPSOs may not have requested an ExternalClearingSystemIdentification1Code in the ISO 20022 External Code Set. They will need to register a code before going live on Nexus.
{% endhint %}

### Message transformation by Nexus <a href="#toc159257082" id="toc159257082"></a>

When an acmt.023 travels through Nexus, Nexus will update the Assignee as follows:

* For proxy resolution requests, the Assignee will be updated to the relevant Destination IPS or Destination PDO depending on the local implementation OR
* For account resolution requests, the Assignee will be updated to the Creditor Agent

No other transformations are made.


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