I can't add pay option in invoice.When ever i send invoice to my customer there is no option of " pay now" kindly help me in solving this problem thanks.

Good thing you posted here in the Community. Let me share some information about why your customer can't access the Pay Now button when paying invoices.

At this time, the feature to turn on payments by adding the pay button is unavailable for QuickBooks Online South Africa. That said, I'd recommend looking for a third-party application that integrates with QuickBooks to handle your online payment methods. You can visit our QuickBooks Apps page.

You can also read this article to learn how to find, download, and manage third-party apps within QuickBooks: Integrate apps in QuickBooks Online.

After you process a payment from a customer, you need to record it in QuickBooks so the invoice is marked as paid. Refer to this article for more details: Record invoice payments in QuickBooks Online

If you have any additional questions about how your customers can pay their invoices in QuickBooks, just hit the reply button below. I'll be around to lend a helping hand.