Find and open the Job from the Diary, Job List or Invoice List
You will find the payment option at the bottom of the Job Maintenance screen - shown below:
Click Select Payment Method and add the amounts your customer has paid against the relevant payment type.
Then click Submit Payment:
🔥Tip: You can even submit a payment before the invoice is generated, this is what we call a Prepayment.
When a job or invoice has a payment against it, you can view details of the payment by clicking the little arrow next to the amount due: