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Reference

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Quick lookups. No explanations, just the data you need.

How to Use This Section​

This reference section is designed for quick lookups, not learning. Use it when you:

ScenarioGo To
Transaction declined, need to know whyDecline Codes
Got a chargeback, need the reason code meaningReason Codes
Need to know how long you have to respondTime Frames
Saw an acronym you don't knowAcronyms or Glossary
Want to know if your metrics are normalBenchmarks
ACH payment bouncedACH Return Codes

Want to understand concepts instead? Start with the main sections:

Typical Range Disclaimer

All ranges marked "Typical" in this reference section assume US domestic transactions with standard risk profiles. Your actual numbers will vary based on your MCC, customer base, transaction mix, and geography.

What's Not Covered Yet

This site doesn't yet cover in depth:

  • Marketplace/PayFac operations and compliance
  • Crypto and stablecoin payments
  • Cross-border payout optimization
  • Card program management (issuer-side deep dives)

These may be added in future updates.

Popular
❌
Decline CodesPopular
Why transactions fail
🔢
Reason CodesPopular
Chargeback category lookup
⏰
Time FramesPopular
Response deadlines by network
📊
BenchmarksPopular
What 'good' looks like
📖
Glossary
Definitions and terminology
What You Need Right Now
❓
"Why was this declined?"
Decline codes explain authorization failures
❓
"What's this reason code?"
Reason codes explain chargeback categories
❓
"When do I have to respond?"
Deadlines by network and stage
❓
"What does this mean?"
Acronyms: AVS, CVV, ARN, TC40...
Card Networks

Card networks make the rules. Understanding Visa vs Mastercard vs Amex vs Discover helps you know which thresholds and programs apply to you.

🌐
Card Networks Overview
Visa, Mastercard, Amex, Discover - who does what and which rules matter
💳
Visa
VAMP 0.9% threshold, 30-day response, strictest monitoring
🔴
Mastercard
ECM 1.0% threshold, 45-day response, MATCH list operator
🔵
American Express
Closed-loop, inquiry process, 20-day response, premium cardholders
🟠
Discover
Smallest network, ~1.0% threshold, 20-30 day response
Reason Codes by Network

Every chargeback has a code. The code tells you why and what evidence you need.

💳
Visa
10.4 (fraud), 13.1 (not received), 13.2 (cancelled recurring)
🔴
Mastercard
4837 (fraud), 4853 (dispute), 4834 (POI error)
🔵
Amex
F29 (fraud), C08 (goods not received), C28 (cancelled recurring)
🟠
Discover
UA02 (fraud), RG (not received), AP (recurring)
Decline Codes

Decline Codes - Authorization decline reasons and what to do about them.

Common ones you'll see constantly:

  • 05 (Do Not Honor) - Generic decline, retry might work
  • 51 (Insufficient Funds) - Card maxed out
  • 14 (Invalid Card Number) - Typo or test card
  • 54 (Expired Card) - Update card on file
ACH Return Codes

ACH Return Codes - Why ACH transactions bounce.

The ones that matter:

  • R01 (Insufficient Funds) - Most common, can retry
  • R10 (Unauthorized) - Chargeback equivalent, 60 days
  • R29 (Corporate Unauthorized) - Same as R10, corporate account
Response Deadlines

Time Frames - Miss these and you automatically lose.

NetworkRepresentmentPre-ArbArbitration
Visa30 days30 days10 days
Mastercard45 days30 days10 days
Amex20 days45 daysN/A
Discover20 daysN/AN/A
Terminology
📖
Glossary
Definitions and terminology
🔤
Acronyms
AVS, CVV, ARN, TC40, etc.
🔍
Fraud Classification
Identify fraud types and responses

Next Steps​

Looking up a code?
  1. Decline Codes - Auth failures
  2. Reason Codes - Chargeback categories
  3. ACH Return Codes - Bank returns
Need context?
  1. Payments Overview - How transactions work
  2. Chargebacks Overview - Dispute process
  3. Fraud Types - Threat landscape
Building a process?
  1. Benchmarks - What "good" looks like
  2. Time Frames - Critical deadlines
  3. Experimentation - Test safely

See Also​

💳 Payments💰 Chargebacks🔍 Fraud Types📋 Compliance