I have a customer that is getting a note that her payment is declined, using multiple methods and amounts, while QuickBooks is telling me no payments have been initiated.

I want to make sure your customer can successfully process payments in QuickBooks Online (QBO) without encountering any problems, bofagandecology.

If you're using  QuickBooks Payments, you can process customer payments directly from QuickBooks products. We can check for common issues that may cause your customer's credit cards to be declined. 

• The info they entered may not match what the bank has on file.
• The payment amount might be larger than the limit set by the card issuer or bank.

• Card restrictions: Some debit cards restrict online transactions or specific merchant categories. Contact your bank to ensure that your card is authorized for online purchases and that there are no restrictions.
• Security measures: Banks and credit card companies have fraud detection systems that may flag certain transactions as suspicious. If this happens, your card issuer may decline the transaction to protect your account. Contact your bank to confirm if this is the case and to authorize the transaction.

If a card is declined, we recommend your customer check with their bank. 

I have included an excellent resource for assistance with receiving and handling online payments: Take and process payments with QuickBooks Payments.

If you require further help with processing payments, feel free to leave a comment below. I've got you covered.