Personal Identification Number (PIN)

Overview

A Personal Identification Number (PIN) is a short numerical code used to verify a person’s identity for electronic transactions and device access. PINs are most commonly associated with debit and ATM cards but are also used for mobile devices, security systems, and some tax filings. Typical PIN length is four to six digits.

How PINs work

• PINs add a layer of authentication during transactions. When you enter a PIN at an ATM or point of sale (POS), it confirms you are the authorized cardholder.
• In card payments, a transaction flow usually involves the merchant, the acquiring bank, the payment network, and the issuing bank. A correct PIN provides the issuing bank with stronger evidence that the card is in the rightful user’s hands.
• PIN verification is handled by secure payment networks and banks using cryptographic methods; card numbers themselves are validated by checksums (for example, the Luhn algorithm), while PINs are confirmed through secure authorization messages between banks.

PINs vs. passwords

• PIN: typically numeric, short (4–6 digits), fast to enter, often stored or verified locally or within secure payment systems.
• Password: usually longer, can include letters, numbers, and symbols, and is generally used for online accounts where stronger protections (hashing, server-side controls, multi-factor authentication) apply.
• Use a PIN for quick, local authentication (cards, devices); use complex passwords for accounts and services that require stronger resistance to remote attacks.

Best practices for creating and protecting PINs

• Avoid obvious combinations: do not use sequential (1234), repeated digits (0000), or easily discovered personal dates (birthdays, anniversaries).
• Prefer longer PINs (if allowed) — 6 digits is stronger than 4.
• Choose a number that’s memorable to you but hard for others to guess.
• Don’t reuse the same PIN across multiple accounts or cards.
• Change your PIN periodically, especially if you suspect it has been exposed.
• Keep your PIN secret: never write it on the card, share it, or store it unprotected.
• Shield the keypad when entering your PIN at ATMs or terminals and be alert for skimming devices or suspicious equipment.

Card security and merchant transactions

• At the POS, entering a PIN provides two-factor-like protection: possession of the card plus knowledge of the PIN.
• Some terminals and countries rely on chip-and-PIN (EMV) systems; contactless or signature-based transactions may not require a PIN for small amounts, depending on settings and risk thresholds.
• Issuing banks perform additional checks (fraud rules, available balance) before approving a transaction that includes PIN verification.

Special note: IRS Identity Protection PIN

The IRS issues a six-digit Identity Protection PIN (IP PIN) to eligible taxpayers to help prevent tax-related identity theft. It is separate from banking PINs and is used only for tax-filing authentication.

FAQs

• How do I recover a forgotten PIN?
  Contact your bank or card issuer. After verifying your identity, they can reset or reissue a PIN and guide you on activation.
• Do all debit cards use a PIN?
  Yes, debit cards are linked to a PIN, though some transactions (e.g., certain contactless or signature-based purchases) may not require entering it.
• Is a CVV the same as a PIN?
  No. A CVV (card verification value) is a number printed on the card used to validate card-not-present transactions (online, by phone). A PIN authenticates the cardholder in person.
• How do I activate a new card’s PIN?
  Activation methods vary: entering the card at an ATM and setting a PIN, calling an activation number, or following issuer instructions online or in-branch.

Bottom line

A PIN is a simple, effective method of authenticating identity for many in-person financial transactions and device access. Choosing a non-obvious, sufficiently long PIN and guarding it carefully significantly reduces the risk of unauthorized use.