Reference

TL;DR

• Quick lookups, not learning. Find the code, the threshold or the deadline and get back to work
• Decline Codes for why a transaction failed. Reason Codes for why a chargeback was filed
• Time Frames for how long you have to respond. Miss that window and you lose automatically
• Want the concepts instead? Start at Payments, Chargebacks or Fraud

How to Use This Section

Find what you're after:

Scenario	Go To
Transaction declined, need to know why	Decline Codes
Got a chargeback, need the reason code meaning	Reason Codes
Need to know how long you have to respond	Time Frames
Saw an acronym you don't know	Acronyms or Glossary
Want to know if your metrics are normal	Benchmarks
ACH payment bounced	ACH Return Codes

Need the why, not the code? Start here:

• Payments - How transactions work
• Chargebacks - Dispute process explained
• Fraud - Prevention and detection

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Typical Range Disclaimer

Everything marked "Typical" here assumes US domestic transactions at standard risk. Your numbers will differ. MCC, customer base, transaction mix and geography all move them.

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)

Might add them later, might not.

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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

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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...

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Card Networks

Card networks make the rules. Which one you're on decides your thresholds and programs.

🌐

Card Networks Overview

Visa, Mastercard, Amex, Discover - who does what and which rules matter

💳

Visa

VAMP program, 30-day response, processors flag at ~0.9%

🔴

Mastercard

ECM 1.5% 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

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Reason Codes by Network

Every chargeback has a code. The code tells you why. It also tells you what evidence you'll need to fight it.

💳

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)

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Decline Codes

Decline Codes - why an authorization failed, and what you can do about it.

The ones you'll see constantly:

• 05 (Do Not Honor) - the issuer's shrug. A retry sometimes works
• 51 (Insufficient Funds) - there's no money there
• 14 (Invalid Card Number) - a typo, or a test card
• 54 (Expired Card) - you'll need a fresh card on file

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ACH Return Codes

ACH Return Codes - why ACH payments bounce.

The ones that matter:

• R01 (Insufficient Funds) - the common one. You can retry
• R10 (Unauthorized) - it's the ACH chargeback. 60 days
• R29 (Corporate Unauthorized) - R10's corporate twin

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Response Deadlines

Time Frames - miss one and you've lost automatically.

Network	Representment	Pre-Arb	Arbitration
Visa	30 days	30 days	45 days
Mastercard	45 days	30 days	45 days
Amex	20 days	45 days	N/A
Discover	30 days	N/A	N/A

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Terminology

📖

Glossary

Definitions and terminology

🔤

Acronyms

AVS, CVV, ARN, TC40, etc.

🔍

Fraud Classification

Identify fraud types and responses

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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

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See Also

💳 Payments💰 Chargebacks🔍 Fraud Types📋 Compliance

• Fraud Prevention - Stopping fraud
• Operations - Operational processes
• Playbooks - Step-by-step guides
• Network Programs - VAMP, ECM thresholds
• 3D Secure - Authentication
• AVS & CVV - Verification signals
• Chargeback Metrics - Tracking disputes
• Fraud Metrics - Measuring performance