Short answer
A Square test CVV is a fake 3 or 4 digit security code entered with a Square sandbox test card number. Square accepts any 3 digit value for Visa, Mastercard, Discover, JCB, and Diners Club test cards. Use 4 digits for American Express. No issuer checks the value, because sandbox payments never reach a card network.
Square Test CVV Guide: How to Use CVV for Secure Transactions
Steps
- Sign in to the Square Developer Dashboard and set the application to Sandbox.
- Copy a test card number from the Square test values page.
- Enter a future expiration date, for example 12/2030.
- Enter any 3 digit CVV. For American Express cards, enter 4 digits.
- Enter any 5 digit US ZIP code and any cardholder name.
- Submit the payment and read the response. A sandbox approval returns a payment ID and a status of APPROVED.
Test card numbers
- Visa: 4111 1111 1111 1111
- Mastercard: 5105 1051 0510 5100
- American Express: 3400 000000 00009
- Discover: 6011 0000 0000 0004
- JCB: 3569 9900 1009 5841
- Diners Club: 3000 000000 00004
CVV decline tests
Square also lists test card numbers that force specific declines, including CVV mismatch and expired card responses. The exact numbers sit on the test values page for your API version. Square changes those values between versions, so read the page that matches the version in your account.
Rules and limits
- Never enter a real card number, CVV, or expiration date in sandbox. PCI DSS rules cover live cardholder data.
- Sandbox and production use different credentials, different hosts, and different API keys.
- Test card numbers fail in production. Live cards fail in sandbox.
- Do not store test account numbers as if they were cardholder data.
Unknowns
Square does not publish one fixed CVV per test card across all API versions. Confirm the value in the documentation for the version tied to your account. If the sandbox rejects your CVV, check the expiration date first. Square rejects past dates before it looks at the CVV.