client is taking forever to pay

We can establish late fees for overdue invoice payments from your clients and set a default fee amount in your QuickBooks Online (QBO) settings, Mike.

Before proceeding, we can send a reminder to your clients to notify them that their invoice payment is overdue.

Here's how:

1. Click on the Gear icon.
2. Navigate to Account and Settings.
3. Select the Sales tab.
4. In the Reminders section, click the pencil icon to customize and set up reminder emails.

To set up late fees for overdue invoices. Here's how:

1. Go to the Gear icon and select Account and Settings.
2. Navigate to the Sales tab, then locate the Late fees section and click the pencil icon to edit.
3. Turn on the Default charge applied to overdue invoices.
4. Specify the Amount and/or Percent for the late fee.
5. Click on the Frequency dropdown to select how often customers will be charged the fee.
6. (Optional) Set a grace period by choosing the number of days from the dropdown menu.
7. (Optional) Edit the default name Late fee.
8. Click Save.

Also, please communicate directly with your client and discuss the overdue invoice payments.

To understand how QuickBooks Online applies automatic late fees to overdue invoices. Please refer to this article: Understand automatic late fees in QuickBooks Online.

For clarification, you can always come back to this thread.