How to record payments today for future services and not mess up this month's P&L

Good day, Bruce J.

The best way to record this payment is by a retainer. This is a deposit or advance payment from your clients that we consider as a liability until we apply it as a payment to your invoices or sales receipt.

The first thing we need to do is to create a liability account where we'll record the funds. You can follow these steps:

1. Go to the Accounting tab and select Chart of Accounts.
2. Select New. Choose Current Liabilities as your Account Type and Trust Accounts - Liabilities for the Detail Type.
3. Enter the other details, then Save and close.

Once done, create a service item for the retainer and use the liability account you set up as its income account. Then, use a sales receipt to record the deposit.

You can also refer to this link for the detailed steps: Record a retainer or deposit. It'll also show you how to apply it when you record the final sale transaction.

Please post again if you need anything else. Wishing you all the best!