Hi there, AnneB.

Yes, you need to create invoices to post rent payments to the Profit and Loss (P&L) report. 

The P&L summarizes the total income and expenses of your business at a specific time. This means that all of your income and expense transactions (invoices, sales receipts, bills, checks, credit memo/refund) recorded in QuickBooks will post to this report.

If you want, you can browse this article as a reference on how we also track rentals in QuickBooks Desktop: Record transactions for a property management company. It can help you manage the two company files at the same time as mentioned by JenCTP.

Get back to me if there's anything else you need by commenting below. I'll be right here to answer your questions.