CASS Practice Test

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.

CASS Exam at a Glance

What the CASS is and how it works

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.

Worked examples: how to reason through CASS questions

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.

Example 1

Question: How are ambiguous addresses handled?

1. Ignored
2. Use extra data to clarify
3. Assumed incorrect
4. Discarded

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.

• A (ignored) leaves the record unprocessed and gives the mailer nothing to act on.
• C (assumed incorrect) and D (discarded) lose addresses that may be fully deliverable once the missing detail is found.

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.

Example 2

Question: What is 'SuiteLink' used for in address hygiene processing?

1. Appending secondary address information to business addresses
2. Validating rural route addresses
3. Converting PO Boxes to street addresses
4. Identifying deceased individuals in a mailing list

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.

• B is wrong because rural route handling is a different job. Converting rural-route-style addresses to city-style addresses is what LACSLink does, not SuiteLink.
• C is wrong because a PO Box is its own delivery point. SuiteLink does not turn it into a street address.
• D is wrong because identifying deceased individuals is a list hygiene service outside address matching. SuiteLink uses business address data, not personal records.

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.

Example 3

Question: When a CASS professional encounters an unfamiliar challenge in delivery point barcode standards, what is the recommended first course of action?

1. Proceed based on personal intuition alone
2. Research applicable standards, consult with subject matter experts, and document the approach
3. Postpone addressing the issue indefinitely
4. Apply the solution used for the most recent similar problem without adaptation

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.

• A is wrong because intuition alone cannot be checked against the specification and is easy to get wrong.
• C is wrong because putting the issue off indefinitely leaves the gap in place, and it can surface later as failed records.
• D is wrong because reusing the last fix without adapting it assumes the two problems are identical. Barcode rules often depend on the specific address case.

Rule to remember: for anything unfamiliar, look up the standard, get informed input and document your reasoning.

How to use these practice tests

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.

1. Read the current CASS Technical Guide first. Note which categories need a perfect score and which need 98.5%.
2. Start with the categories that need a perfect score. Work through Delivery Point Barcode Standards, DPV processing and Address Hygiene and Data Quality, which covers SuiteLink.
3. Cover the matching logic next. Use Address Matching and Standardization, Postal Address Verification and USPS Addressing Standards.
4. Trace every miss back to the guide. For each wrong answer, find the rule it depends on and check how your software handles it.
5. Use Stage I as a rehearsal. Stage I comes with answers, so compare your output against them category by category.
6. Check your output before Stage II. Review Output Records and Certification Reporting, and leave time for the 10 day grading turnaround.

Sources & last verified

1. United States Postal Service — number of questions, validity, renewal, delivery (official source). “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…” Verified Oct 22, 2026.
2. United States Postal Service — passing score, score release (official source). “Delivery Point Barcode, eLOT, Perfect Address, DPV®/DSF2®, RDI™ and SuiteLink® categories require a 100% score. All other categories require a score of 98.5% accuracy.” Verified Oct 22, 2026.
3. pe.usps.com — exam fee (official source). “CASS (Coding Accuracy Support System) Fee CASS Certification per test $1,330.00” Verified Oct 22, 2026.

How we verify: editorial & fact-checking policy. Report an error: contact us.