Tokenized Account Numbers in US Institutions — What to Expect

Topic: How Flinks handles tokenized account numbers from US open banking institutions  |  Product: Flinks API (Connect)  |  Effort: Reference — no integration changes required

1. Which Institutions Return a TAN

The following institutions are confirmed to return a tokenized account number instead of the real account number when aggregated via open banking:

Chase — TAN Details

Chase defines the TAN as:

"The Tokenized Account Number (TAN) is a secure method for our partners to share an account number that can be used for ACH or RTP transactions instead of the actual account number. Using a TAN reduces the risk of a customer's account number being compromised."

Chase issues TANs for these deposit account types:

• CHK — Checking
• SAV — Savings
• PPG — Starbucks Account
• PPX — Prepaid Liquid Debit Account
• MMA — Money Market Account

Chase TANs are 17 digits in length — longer than a standard account number. This is the clearest signal that tokenization is in effect.

PNC — TAN via The Clearing House

PNC, uses The Clearing House to generate its tokenized account number. The API behavior is the same: a surrogate account number is returned in place of the real account number, and the routing number is provided alongside it.

2. How Flinks Maps the Data

When Flinks aggregates an account that returns a TAN, the /GetAccountsDetail and /GetAccountsSummary response fields map as follows:

Example Response Snippet

{
  "TransitNumber": "021000021",
  "InstitutionNumber": null,
  "AccountNumber": "xxxxxxxxxxxx",
  "LastFourDigits": "2044"
}

LastFourDigits Availability

The LastFourDigits field was added on July 19, 2023 for Chase. It contains the last 4 digits of the customer's actual account number (not the TAN).

• Available on both /GetAccountsDetail and /GetAccountsSummary
• Only populated for OAuth connections where the institution returns this data
• Can be used with TransitNumber to uniquely identify an account across sessions

3. Using TANs for Payment Processing

The TAN and routing number together are sufficient for ACH and RTP payment transactions. No additional data is required.

4. FAQ

Can Flinks retrieve the real account number?

No. The real account number is never transmitted to aggregators by these institutions. This is enforced at the bank's API level. Flinks returns exactly what the institution provides — there is no workaround.

Will the TAN ever change?

This is not fully confirmed for all institutions. For Chase, the TAN is issued per aggregator relationship and is intended to be stable. If TAN stability is a concern, use LastFourDigits + TransitNumber as the stable identifier for account matching on your side.

Does the real account number match the TAN?

No. The TAN is a completely different number. The only connection to the real account is the LastFourDigits field (where available).

Do all US institutions return a TAN?

No. Only institutions that have adopted open banking tokenization policies return a TAN. Many US institutions still return their real account number. TANs are currently confirmed for Chase and PNC.

How do I uniquely identify an account if the TAN might change?

Use the combination of LastFourDigits + TransitNumber. The LastFourDigits value represents the last 4 digits of the customer's actual account number and should remain stable for the same account across sessions.

Is the TAN masked in the Flinks response?

The AccountNumber field is shown as xxxxxxxxxxxx in the API response. This is a Flinks-side display decision. The underlying TAN is stored and available for payment processing use.

5. Quick Reference

6. Related Resources

• Chase TAN Developer Documentation — Official Chase TAN guide
• Flinks /GetAccountsDetail API Reference — Full field reference
• Flinks /GetAccountsSummary API Reference — Summary endpoint reference
• Flinks /Institutions/RoutingNumber — Routing number lookup for US institutions
• The Clearing House — Background on TCH tokenization

Last updated: 2026-03-16  |  Owner: Walter Jr — wrgiannetti@flinks.com