I need to deduct an expense from an income statement received - one for every property. How?

I'll make sure you can deduct an expense from an income you've received in QuickBooks Online (QBO), @john-robilliard-.

You'll have to record billable expenses to deduct an expense from an income for each of your properties. Billable expenses are those you incur when you perform work for your customer. 

To do this, you'll first have to turn on billable expense tracking from the Account and Settings page. Here's how:

1. Go to the Gear icon.
2. Select Account and settings.
3. Choose the Expenses menu.
4. Click the Bills and expenses section to open its details.
5. Turn on the following: Show Items table on expense and purchase forms, Track expenses and items by customer, and Make expenses and items billable. Setting up Markup rate and Billable expense tracking is optional.
6. Bill payment terms.
7. Select Save. 

Once you're done, go ahead and enter a billable expense to bill a customer (property) for an expense. Then, add it to your invoice. This will link the billable expense to your customer's invoice and reimburse the cost. For the step-by-step guide, please refer to this article, starting with Step 2 to 3: Enter billable expenses.

Also, to further guide you about billable expenses and how you can manage them in QBO, I'd recommend checking out this article: What are pay rates, cost rates, and billable rates?. It includes topics about pay rates and cost rates.

Let me know if you have other concerns about managing billable expenses in QBO. You can drop a comment below, and I'm always ready to help. Take care, and I wish you continued success, @john-robilliard-.