CASS Cheat Sheet 2026

The 30 highest-yield CASS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. USPS charges a Move Update non-compliance surcharge on which class of mail? → Both First-Class Mail and Marketing Mail
2. In the context of CASS certification, what is the most important consideration when implementing presort & mail preparation? → Ensuring alignment with established standards, stakeholder needs, and best practices
3. Why is annual certification required? → Maintain postal compliance
4. What is the benefit of complying with USPS addressing standards? → Better deliverability and discounts
5. What is the consequence of using uncertified software? → Mail rejection or lost discounts
6. How are ambiguous addresses handled? → Use extra data to clarify
7. A mailer uses a 9-digit Mailer ID. How many digits long must the Serial Number field be in their Intelligent Mail barcodes? → 6 digits
8. Which USPS electronic service uses Full-Service IMb scan data to automatically provide address correction records to mailers when a piece is undeliverable? → Automated Change-of-Address Service (ACS)
9. Which USPS endorsement instructs the postal service to return undeliverable mail and provide the new address if available? → ADDRESS SERVICE REQUESTED
10. Why is CASS certification important for mailers? → Ensures USPS compliance
11. For USPS acceptance of automated-rate mailings, how current must the CASS processing date on Form 3553 be? → Within 180 days of mailing
12. Which of the following best describes a key competency required for address hygiene & data quality in CASS practice? → Strong analytical skills combined with effective communication and ethical judgment
13. How many digits can a USPS-assigned Mailer ID (MID) contain in the Intelligent Mail barcode? → 6 or 9 digits
14. What minimum ZIP+4 coding accuracy percentage must CASS-certified software achieve on USPS test files? → 98%
15. What is the significance of the CASS 'cycle' date stamped on Form 3553? → It identifies which USPS address file vintage was used during processing
16. What does a high undeliverable-as-addressed (UAA) rate primarily indicate about a mailing list? → The list contains outdated or inaccurate address data
17. Which tool does USPS provide to help mailers identify and correct addresses that are likely to become undeliverable? → Address Element Correction (AEC)
18. Which CASS output indicator confirms that a specific address exists in the USPS Residential Delivery Indicator (RDI) file? → RDI flag field
19. What does CASS software testing evaluate? → Standardize and correct addresses
20. A CASS-certified address standardization process helps reduce return mail primarily by doing what? → Correcting address format errors before mailing
21. When generating a Form 3553, what does the 'Total Records Coded to ZIP+4' figure represent? → Number of records that received a valid ZIP+4 assignment
22. How often should address data be updated? → Regularly updated
23. In the context of CASS certification, what is the most important consideration when implementing ncoa & move update processing? → Ensuring alignment with established standards, stakeholder needs, and best practices
24. What is an Address Matching Key (AMK)? → Indicates address match level
25. In the IMb structure, what does the Barcode ID (BID) field consist of? → 2 digits identifying the presort level and barcode usage
26. What does it mean when a CASS output record has a Carrier Route Code of 'B001'? → It is a Post Office Box section route
27. What CASS output field identifies the specific two-digit delivery point within a ZIP+4 range? → Delivery Point Code (DPC)
28. Which USPS service allows mailers to receive electronic address correction data instead of physical nixie mail? → OneCode ACS
29. In the context of CASS certification, what is the most important consideration when implementing delivery point barcode standards? → Ensuring alignment with established standards, stakeholder needs, and best practices
30. What is an address locator in CASS? → Postal verification tool