How Merchant Payment Processing Works—From Card Swipe to Your Bank Account

What happens when a customer pays you with a card

When a customer hands you a card or taps their phone, that transaction does not go straight into your bank account. It moves through a chain of companies—the card network (Visa, Mastercard, American Express), the customer's bank, a payment processor, and your bank—each taking a small cut and a few days to settle. Understanding this chain matters because it affects how much you pay in fees, when you see the money, and what happens if something goes wrong.

The payment processor is the company you contract with directly. They handle the technology that reads the card, sends the transaction to the card network, and eventually deposits funds into your business bank account. Common processors include Square, Stripe, PayPal, Toast, and Clover, though there are dozens more. Your processor is also your first point of contact if a customer disputes a charge or a transaction fails.

The whole cycle—from swipe to settlement in your account—typically takes one to three business days, though some processors offer next-day or same-day settlement for a higher fee. During those days, the money sits in a holding account while the card networks and banks confirm the transaction is legitimate and the funds are available.

Key Takeaways

• Your payment processor is the company you sign a contract with; they collect fees and handle disputes, but they do not own the money during settlement.
• Card networks (Visa, Mastercard, Amex) set interchange rates—the percentage the customer's bank charges—which you pay as part of your processing fee.
• Settlement time varies by processor and account type, ranging from one to three business days, and faster settlement costs extra.
• Chargebacks happen when a customer disputes a charge with their bank instead of asking you for a refund, and they cost you the transaction amount plus a fee.
• Flat-rate pricing (like 2.9% plus $0.30 per transaction) is simpler to budget but often costs more than interchange-plus pricing if you process high volumes.

How fees are built into every transaction

When you see a processing fee, it is usually a combination of three things: interchange, assessment, and processor markup. Interchange is the percentage the customer's bank charges the card network for processing the transaction—this is set by Visa or Mastercard, not by your processor, and varies by card type and industry. A rewards credit card might have 2.2% interchange; a debit card might be 0.05%. Your processor passes this cost to you.

Assessment is a smaller fee the card network itself charges, usually 0.1% to 0.15%. Processor markup is what your processor keeps as profit. On a $100 transaction with 2% interchange, 0.1% assessment, and 0.5% processor markup, you pay $2.60 total—but you only see the combined percentage on your statement.

Two pricing models exist. Flat-rate pricing bundles everything into one percentage plus a per-transaction fee (like 2.9% plus $0.30). This is predictable and easy to budget, but you pay the same rate whether the customer uses a basic debit card or a premium rewards card. Interchange-plus pricing separates interchange from processor markup, so you see exactly what Visa charges and what your processor keeps. Interchange-plus is usually cheaper if you process high volumes or many debit cards, but it requires reading a more complex statement.

Settlement: when money actually reaches your account

Settlement is not the same as authorization. When a customer's card is approved at the register, that is authorization—the bank confirms the funds exist. Settlement happens later, when the processor batches all your transactions for the day and sends them through the card networks to the banks. The banks then move money from customer accounts to your processor's account, and your processor deposits it into your business bank account.

Standard settlement takes one to three business days. Some processors offer next-business-day settlement at no extra cost if you meet volume thresholds; others charge 0.5% to 1% extra for same-day or next-day settlement. Weekends and holidays extend the timeline—a transaction authorized on Friday may not settle until Tuesday. If you need cash quickly, faster settlement is worth the cost; if you can wait, standard settlement saves money.

During the settlement window, your processor holds the money. This is why chargebacks are possible—if a customer disputes the charge during those days, the processor can reverse the transaction before your bank account is credited. Once settlement completes and the money is in your account, chargebacks still happen, but the processor pulls the money back out, leaving you with a negative balance or a charge to cover the reversal.

Chargebacks: disputes that cost you twice

A chargeback occurs when a customer contacts their bank and disputes a charge instead of asking you for a refund. The bank pulls the money back from your processor and charges you a fee—usually $15 to $100 depending on the processor and card network. You lose the transaction amount plus the fee, and your chargeback rate is tracked. Too many chargebacks (usually more than 1% of your transaction volume) can result in higher fees, mandatory reserves, or account termination.

Common chargeback reasons include "I did not authorize this," "the product never arrived," "the product was not as described," and "the merchant charged me twice." Some are legitimate customer complaints; others are fraud or buyer's remorse. You have the right to dispute a chargeback by providing evidence—a signed receipt, a tracking number, an email confirmation, a photo of the delivered item—but the burden is on you to prove the transaction was legitimate.

Prevention is cheaper than fighting chargebacks. Keep clear records of every transaction, send order confirmations and tracking numbers by email, use clear business names on statements so customers recognize the charge, and make your refund policy visible at checkout. For high-risk transactions (large orders, international cards, card-not-present sales), ask for additional verification like a CVV or a billing address match.

Choosing between payment processors

Processors differ in pricing, settlement speed, features, and support. A retail business with a physical location might choose Square or Clover for their point-of-sale systems and in-person card readers. An online store might choose Stripe or Shopify Payments for their integration with e-commerce platforms. A restaurant might use Toast for its table management and kitchen display features. A nonprofit might use PayPal for its lower rates on donations.

When comparing processors, look at the total cost of a typical transaction, not just the percentage. A processor charging 2.5% plus $0.25 per transaction costs more on small sales than one charging 2.9% plus $0.30. Ask about hidden fees: monthly minimums, PCI compliance fees, gateway fees, batch fees, or early termination penalties. Some processors charge nothing upfront; others require equipment purchases or long-term contracts.

Settlement speed, customer support, and dispute resolution matter too. If you need money fast, compare settlement options. If you process many chargebacks, ask how each processor handles disputes and what evidence they accept. Read reviews from businesses like yours—a processor that works well for a coffee shop might not work for a subscription service.

PCI compliance and fraud prevention

PCI compliance refers to the Payment Card Industry Data Security Standard, a set of rules designed to protect customer card information. If you store, process, or transmit card data, you must follow these rules or face fines and account suspension. Most processors handle PCI compliance for you—they encrypt card data, store it securely, and ensure your systems meet the standard. You are responsible for keeping your devices and software updated, using strong passwords, and not storing sensitive card information like CVV numbers or full card numbers in plain text.

Fraud prevention tools vary by processor. Some offer address verification (checking that the billing address matches the card issuer's records), CVV verification (confirming the three-digit security code), and velocity checks (flagging multiple transactions from the same card in a short time). Others use machine learning to detect suspicious patterns. These tools reduce chargebacks and fraud losses, but they also occasionally block legitimate transactions, so balance security with customer experience.

What to do if a transaction fails or a customer disputes a charge

If a transaction is declined, the customer's bank rejected it—usually because insufficient funds, a mismatched address, or a card that has been reported lost or stolen. Your processor will tell you the decline code. You can ask the customer to try a different card, contact their bank, or use a different payment method. A declined transaction does not cost you a fee.

If a customer says they were charged twice, check your processor's transaction history immediately. Duplicate charges sometimes happen due to network errors or a customer clicking "submit" twice. If a duplicate exists, issue a refund through your processor's dashboard—this is faster and cheaper than waiting for a chargeback. Document the refund in case the customer disputes it later.

If a customer disputes a charge and you receive a chargeback notice, respond quickly. Your processor will give you a deadline (usually 7 to 10 days) to submit evidence. Gather your receipt, order confirmation, shipping proof, or any communication with the customer that shows the transaction was legitimate. Submit everything through your processor's dispute portal. If you win, the money is returned to your account; if you lose, you keep the chargeback fee.

Frequently Asked Questions

Why does my processor hold money for a few days instead of depositing it immediately?

Settlement takes time because the money has to move through multiple banks and card networks, and they need time to confirm the transaction is legitimate and the funds are available. Your processor also batches transactions to reduce costs. Faster settlement is possible but costs extra because it requires the processor to front the money before the banks confirm it.

Can I use the same processor for online and in-person payments?

Yes, most major processors support both. You will need different hardware—a card reader for in-person payments, a payment gateway for online payments—but the same account and pricing. Some processors charge different rates for card-present (in-person) versus card-not-present (online) transactions because card-not-present has higher fraud risk.

What happens if my processor goes out of business?

Your money in settlement should be protected, but the transition can be messy. You will need to set up a new processor and update your payment systems. To minimize disruption, keep your processor's contact information and settlement account details in a safe place, and monitor industry news about processor stability. Larger, established processors are lower risk than startups.

Do I have to accept all card types, or can I refuse American Express?

You can refuse any card type, but it is rare because you lose sales. Amex charges higher interchange rates than Visa or Mastercard, so some businesses refuse it to save on fees. If you do, you must disclose this clearly at checkout so customers know before they try to pay.

How do I know if my processing fees are competitive?

Compare the total cost of a typical transaction across three to five processors, not just the percentage. Ask each processor for an itemized statement showing interchange, assessment, and markup separately. If you process high volumes, get quotes for interchange-plus pricing. If you process low volumes, flat-rate pricing may be simpler and cheaper.