I have a customer that has no option to pay invoices on line what am I doing wrong? This is a regular customer I invoice every week.

I've got the reason why your customer can't pay their invoice in QuickBooks Online (QBO), mcs12015.

To start, have you already signed up for QuickBooks Payments? Does it apply to that specific customer? If so, please ensure you've turned on the accept online payments options when creating the invoice because that's the possible reason why your customer can't pay.

Moreover, if you confirm that QuickBooks Payments is set correctly and the invoice settings are appropriate, but the issue persists, I recommend contacting QuickBooks Payments support for further assistance. They have specialized tools and resources to investigate this matter in detail and provide a permanent solution tailored to your situation.

Furthermore, I'll be dropping this article you can browse for you to learn more about how to help your customers if they can't pay for an invoice you sent: What to do if customer can't pay their invoices online. 

Your success is important to me, and I look forward to assisting you further whether it's creating invoices or managing payments. Wishing you continued success in your business.