CASS-Certified vs Non-Certified Address Validation
One unlocks postage discounts. Both can clean your data. A side-by-side view of what each gives you and when each is the right tool.
CASS-certified software has passed a postal accuracy test and can print PS Form 3553, the report you need to claim automation and carrier route postage prices on bulk mail. Non-certified validation cannot unlock those prices. It can still standardize addresses, check deliverability and flag bad apartment numbers, which is what checkout forms and CRM cleanup need.
Side by side
| CASS-certified | Non-certified | |
|---|---|---|
| Automation and carrier route postage prices | Yes, with PS Form 3553 | No |
| Proven minimum accuracy | 98.5% ZIP+4, 100% delivery point coding, on the postal test file | Depends on the vendor. Ask for results on messy input |
| Renewal | Every two years. Cycle O ends July 31, 2028 | None |
| Includes DPV, LACSLink, SuiteLink | Required as part of certification | Varies by vendor |
| Standardized address and ZIP+4 | Yes | Often yes |
| Deliverability signal | Yes (DPV) | Often yes |
| Handles typos and messy input | Not part of the test | Not part of any test. Measure it yourself |
| Best for | Bulk mail that claims postage discounts | Checkout, signup, CRM cleanup, parsing, data quality |
The certification test uses a postal test file. It proves that software codes addresses correctly to a high standard. It does not measure what happens when a customer types "2 emreald ln doevr new hmapshire". If most of your addresses come from people typing into a form, test that case directly. Our guide on how to test an address API's accuracy shows how.
Which one to choose
- You mail large volumes at discounted prices. You need CASS-certified software for that step. There is no way around PS Form 3553.
- You collect addresses at checkout or signup. Certification is not what matters. Speed, unit-number checks and how the API handles typos matter more.
- You clean a CRM or a spreadsheet. Look at how the tool handles messy input and whether it flags what it changed.
- You do both. Use an API at the point of entry, then run the final mailing list through CASS-certified software before the drop.
Where sthan.io fits. sthan.io is not CASS-certified. It is built for the point of entry and for cleanup: deliverability status, unit type and number as separate fields, ZIP+4, and a parser that refuses to guess when a house number does not exist.
How vendors talk about CASS
Many API vendors show "CASS certified" as a badge on products that are also used for checkout and CRM work. That is accurate for their software, and it matters if you mail. It does not by itself tell you how the API handles messy input, what it does when it cannot find a match, or what it costs at your volume. See how address verification APIs are priced for public prices side by side.
Frequently Asked Questions
Sources
- PostalPro CASS certification page and CASS Technical Guide, Cycle O (postalpro.usps.com), read September 27, 2026
- Domestic Mail Manual 602, section 9 (pe.usps.com), read September 27, 2026
Clean addresses at the point of entry
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