A lot of my transactions are getting declined. Anyone knows why?

If it is some but not all, it could be a security issue, I used to have this problem processing recurring monthly subscriptions, any new clients had to call their bank and get approved so you can process or use their bank app to verify.  Some clients have this security setting on their accounts and don't even realize it. 

I want to ensure that you can successfully process payments in QuickBooks. I will provide you with potential reasons why the payments may have been declined. This information will assist you in seamlessly processing the payment in QuickBooks Online (QBO).

Before proceeding, have you encountered any error messages? If you have, it would be helpful if you could provide me with the specific error message you encountered. This information will help us identify the issue and provide you with accurate solutions.

Usually, payments are declined due to the following reasons:

• Invalid account number
• Expired credit card
• Over-limit or past due
• The processor denied providing any other information.
• The issuing bank will not electronically authorize the credit card.
• The billing address in QuickBooks Online does not match the address on your statement.

Here are some tips and steps you can take to resolve the issue:

• Ensure the credit card number and verification code (usually on the back of the card) are correct. Most credit card numbers are 16 digits long. American Express cards are 15 digits long.
• In addition to the credit card number, you need to enter a verification code. Most cards, such as Visa, Mastercard, and Discover cards, have a 3-digit code on the back. For American Express, it's the 4-digit code on the front of the card.
• Ensure there are no special characters or spaces in the credit card number or other data fields.
• Use the customer's address from the US USPS website.

For additional instructions, read the details from this link: Fix customers declined credit card payments.

If none of the solutions works for you, you can check with your bank for any possible reason why the payment was declined or if there's an alert or notification about those declined payments.

Additionally, I've provided these articles for your reference to offer you solutions for declined payments or failed bank transfers: Declined Payments.

Is there anything else I can do to assist you with declined payments, or do you have any other questions in QBO? You can always reach out to us if you need further assistance. Have a great day!