Inside a Card Transaction: Auth, Clearing, Settlement Explained

When you tap your card at a coffee shop, three distinct processes execute across multiple parties in different time windows. Understanding authorization, clearing, and settlement is fundamental to working in payments.

The Players

Before diving into stages, meet the participants:

• Cardholder: You, with your Visa or Mastercard
• Merchant: The coffee shop
• Acquirer: The merchant's bank (processes payments on their behalf)
• Card Network: Visa, Mastercard, Amex (routes messages, sets rules)
• Issuer: Your bank (issued the card, holds your account)

Stage 1: Authorization (Real-Time, <5 Seconds)

The Flow

1. Merchant terminal captures card data (PAN, expiry, CVV) via chip, swipe, or contactless NFC
2. Acquirer receives transaction details: amount, merchant ID, card details
3. Network routes authorization request to the issuer based on card BIN
4. Issuer evaluates:
   • Is the card active and not blocked?
   • Does the account have sufficient funds?
   • Is this transaction consistent with spending patterns (fraud check)?
5. Issuer responds: Approve (00), Decline (05), or Call Issuer (01)
6. Network routes response back to acquirer
7. Terminal displays result to cardholder

Authorization Data

The auth message includes:

• Transaction amount and currency
• Merchant Category Code (MCC): 5812 for restaurants, 5541 for gas stations
• Card-present vs card-not-present indicator
• Terminal capabilities: chip, contactless, PIN-capable

Holds and Reserves

Upon approval, the issuer places a hold on funds. This isn't a transfer—it's a reservation. The actual money movement happens later during settlement.

Edge case: Gas station pre-auths often hold $100-$150, then settle for actual pump amount days later. This is why you see temporary charges larger than what you spent.

Stage 2: Clearing (Batch, Typically End-of-Day)

Hours after the coffee purchase, the merchant submits the transaction for clearing.

The Process

1. Merchant batches all day's transactions (usually end-of-business)
2. Acquirer aggregates transactions from all merchants
3. Network receives clearing files from acquirers globally
4. Network sorts and routes to issuers based on card BIN
5. Issuers receive clearing records with final amounts

Why Clearing Matters

Clearing reconciles authorization with actual transaction details:

• Amount adjustment: Pre-auth $100, actual $87.50 (gas station scenario)
• Tip addition: Restaurant auth $45, clears $54 after 20% tip
• Offline transactions: Subway fare gates without real-time connectivity

Data Enrichment

Clearing messages are richer than auth:

• Full merchant name and address
• Enhanced transaction metadata
• Tax and tip breakdowns (in some jurisdictions)

This is when your bank statement gets populated with "STARBUCKS #8472 SEATTLE WA" instead of just "MERCHANT 12345".

Stage 3: Settlement (Batch, T+1 or T+2)

Settlement is the actual exchange of funds between banks.

The Flow

1. Network calculates net positions: If Bank A's cardholders spent $10M at Bank B's merchants, and vice versa spent $8M, Bank A owes Bank B a net $2M
2. Central bank accounts are debited/credited via wholesale payment systems (Fedwire in US, CHAPS in UK)
3. Acquirer credits merchant's bank account (minus MDR fees)
4. Issuer debits cardholder's account (or adds to credit card balance)

Timing

• Domestic cards: Usually T+1 or T+2 (1-2 business days after transaction)
• International cards: Can extend to T+3 or longer due to currency conversion and cross-border settlement
• Real-time settlement: Emerging in some markets, but not yet standard for card networks

Interchange Fees

During settlement, interchange fees are calculated and transferred. If you bought $100 coffee with a Visa Signature card:

• Merchant receives: ~$97.50 (after ~2.5% MDR)
• Breakdown of MDR:
  • Interchange: ~1.8% goes to issuer (rewards funding, fraud liability)
  • Network fee: ~0.15% to Visa/Mastercard
  • Acquirer margin: ~0.55% to merchant's bank

Authorization vs Settlement Mismatches

What happens when auth and settlement amounts differ?

• Partial reversals: Hotel pre-auths $500, settles $300 after early checkout. Issuer releases $200 hold.
• Incremental auths: Car rental auths $100/day, extends stay and adds $100 more. Multiple auths, one settlement.
• Timeout reversals: Auth approved but merchant never submits for clearing (network disconnects). Auto-reversal after 7-10 days.

Chargebacks: The Exception Flow

If the cardholder disputes a transaction:

1. Issuer initiates chargeback via the network (up to 120 days post-transaction)
2. Acquirer debits merchant's account
3. Merchant can accept or dispute with evidence (proof of delivery, signed receipt)
4. Arbitration: Network decides if merchant evidence stands

Chargebacks reverse the settlement flow. Funds move back from merchant to cardholder.

Key Takeaways

• Authorization is real-time approval, not fund movement
• Clearing provides transaction details and reconciles amounts
• Settlement is the actual money transfer between banks
• Timing varies: auth is instant, settlement is days later
• Fees are calculated during settlement, not authorization

Understanding this three-stage model is critical for building payment products, debugging transaction issues, and explaining why "pending" charges can take days to finalize or reverse.