CASS certification is the United States Postal Service test of address matching software. It is open to software developers, mailers and service bureaus. No person sits an exam. Your software processes a USPS test file, and USPS grades what it sends back. This page explains the Stage II process, the fee, the accuracy targets and renewal. It also links free practice sets on addressing, DPV, barcodes and related topics, so your team can check what it knows before you test.
Numbers in brackets link to the official sources listed under Sources & last verified. Dates that have passed are removed automatically.
| Item | Detail | Source · Verified |
|---|---|---|
| Number of questions (Stage II) | About 150,000 test addresses[1] | United States Postal Service · Oct 22, 2026 |
| Passing score | 98.5% in most categories; 100% for DPBC, eLOT, Perfect Address, DPV/DSF2, RDI and SuiteLink[2] | United States Postal Service · Oct 22, 2026 |
| Exam fee | $1,330 per test[3] | pe.usps.com · Oct 22, 2026 |
| Validity (Cycle O) | Until July 31, 2028 (end of Cycle O)[1] | United States Postal Service · Oct 22, 2026 |
| Renewal | Reapply and pass Stage II again each period[1] | United States Postal Service · Oct 22, 2026 |
| Delivery | Test file processed by your own software and returned to USPS for grading[1] | United States Postal Service · Oct 22, 2026 |
| Eligibility | Software developers, mailers and service bureaus[1] | United States Postal Service · Oct 22, 2026 |
| Score release | About 10 days per test submission[2] | United States Postal Service · Oct 22, 2026 |
According to United States Postal Service, “The CASS™ Stage II file contains approximately 150,000 test addresses that are extracted and presented in the same makeup and mixture as Stage I without answers.”[1]
CASS (Coding Accuracy Support System) is how the United States Postal Service evaluates address matching software. USPS says certification is available to all software developers, mailers and service bureaus who want their address matching software evaluated.
This is not a typical certification exam, because the software is what gets tested. For Stage II, USPS supplies a file of approximately 150,000 test addresses. They come in the same makeup and mixture as Stage I, but without answers. You run the file through your own software and return the output to the CASS Department for grading. USPS gives a 10 day turnaround for each test submission and says this can vary with the number of tests it receives.
Each category is scored separately. Delivery Point Barcode, eLOT, Perfect Address, DPV/DSF2, RDI and SuiteLink require a 100% score. All other categories require 98.5% accuracy.
The USPS fee is $1,330 per test. Certification runs by cycle, and Cycle O expires July 31, 2028. To stay certified for each required period, you must reapply and meet the minimum accuracy requirements in Stage II again.
File layouts, Stage I access and resubmission steps are set out in the CASS Technical Guide on PostalPro (postalpro.usps.com). USPS publishes that guide for each cycle, so check that you are working from the current edition before you plan a test.
Prepare for the CASS - Coding Accuracy Support System Certification exam with our free practice test modules. Each quiz covers key topics to help you pass on your first try.
These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.
Question: How are ambiguous addresses handled?
Answer: B. Use extra data to clarify
Explanation:
B is correct. An address is ambiguous when it could match more than one valid record, or when it is missing a detail needed to pick one. Address matching software does not throw these records away. It looks at extra data to narrow the match to a single record, such as a secondary unit, a street suffix or directional, or the ZIP Code.
If the extra data still cannot settle the match, the record should be returned unmatched or flagged for review, not forced onto a guess.
Rule to remember: never force a match. Resolve the ambiguity with additional data, or report no match.
Question: What is 'SuiteLink' used for in address hygiene processing?
Answer: A. Appending secondary address information to business addresses
Explanation:
A is correct. SuiteLink adds missing secondary information to business addresses. When a business address matches only at the building level because the suite or unit is missing, SuiteLink uses USPS business data to supply that suite or unit number.
Rule to remember: SuiteLink means business addresses and their missing secondary units. It is also one of the categories that must be scored perfectly in Stage II.
Question: When a CASS professional encounters an unfamiliar challenge in delivery point barcode standards, what is the recommended first course of action?
Answer: B. Research applicable standards, consult with subject matter experts, and document the approach
Explanation:
B is correct. When a barcode question is new to you, start with the published standard. For delivery point barcodes, that means the USPS specifications and the CASS Technical Guide. Then get input from colleagues or USPS support staff who know the standard well, and write down what you decided and why. That record lets someone else check the decision later.
Rule to remember: for anything unfamiliar, look up the standard, get informed input and document your reasoning.
The practice sets on this page check that you understand the addressing rules your software has to apply. They do not replace running the official USPS files. Use them so the people who build, test and sign off on the software all share the same understanding.
No. CASS certifies address matching software, not individuals. USPS sends a Stage II file of approximately 150,000 test addresses. Your software processes it, and you return the output to the CASS Department for grading. Software developers, mailers and service bureaus can apply. Our practice questions help your team learn the addressing rules involved, but the certification result depends only on how your software handles the file.
The USPS fee is $1,330 per test, as listed in USPS Notice 123 on pe.usps.com. The fee applies to each test, so plan your budget around how many submissions you may need. Check Notice 123 before you apply, because fees are set by USPS and can change.
It depends on the category. Delivery Point Barcode, eLOT, Perfect Address, DPV/DSF2, RDI and SuiteLink require a 100% score. All other categories require 98.5% accuracy. Each category has to meet its own minimum, so a high overall result will not cover a weak category. The CASS Technical Guide on PostalPro lists the categories in full.
Certification runs by cycle. The current cycle, Cycle O, expires July 31, 2028. To stay certified for each required certification period, you must reapply and meet the minimum accuracy requirements in Stage II testing again. Earlier certification does not carry over automatically.
USPS gives a 10 day turnaround for each test submission. It also says this timeframe can vary with the number of tests it receives for grading. If you have a deadline, such as the end of a certification cycle, submit early enough to absorb a delay.
No. We wrote these questions with AI tools to cover the addressing topics behind CASS, such as DPV, SuiteLink, barcodes and address standardization. The real test is not a question paper. It is an address file that your software processes. Use our sets to check your understanding, and use the official Stage I and Stage II files to check your software.
How we verify: editorial & fact-checking policy. Report an error: contact us.