How do I correct invoice with credit balance -.20c? The next invoice has .20c but customer balance is correct at zero.

I'll share steps on how you can correct the invoice, shilton51.

You can unlink the 20 cents credit from the first invoice and apply it to the next one. Here's how: 

1. Open the invoice where the credit was incorrectly attached to.
2. Click the 1 payment link just below Receive payment or Balance Due.
3. In the Receive Payment window, remove the check mark from the invoice where the credit was applied.
4. Move the check mark to the invoice where the credit should be applied.
5. Click Save and close.

Please see the screenshots below for additional reference. I'll be around if you have other questions.