Bank Accounts
How account numbers are protected
Encryption at rest, hidden by default, and a recorded reveal.
1 min readUpdated Aug 3, 2026
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Bank Accounts
How routing numbers are validated
The ABA checksum, the routing reference directory, and what a warning actually means.
Last updated Aug 3, 20261 min read
A United States routing number is nine digits and carries a checksum. Diversified Check Studio validates that checksum as you type and looks the number up in the routing reference directory.
What the results mean
- Valid and found: the checksum passes and the number matches a known institution.
- Valid but not found: the checksum passes but the number is not in the current directory. This can happen with recent changes. Confirm against a printed check.
- Invalid: the checksum fails. There is a typo somewhere in the nine digits.
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