Can we add cost centre in QB

Yes, you can tag your expense item to multiple projects, @JAGA84.

You'll want to ensure you have created an expense item and enable the Project feature in QuickBooks Online (QBO). This way, you'll be able to add your expense item to your projects. I'll show you how. 

1. Go to the Gear icon.
2. Select Products and services.
3. Click New.
4. Select Service.
5. Add a name for the item.
6. From the Category drop-down, select the category that best describes your product or service. 
7. In the Income account drop-down menu, select an expense account.
8. Fill in the needed information and select Save and Close.

You can also check this article for more details: Add product and service items to QuickBooks Online.

I’d also recommend working with your accountant for additional guidance in choosing the right account for the service item. This way, we can guarantee the accuracy of your accounts after recording this.

Then, to turn on and use the Project feature, you can refer to the steps outlined in these articles:  

• Set up and create projects in QuickBooks Online 
• Track income, costs, and profitability by project

Once done, you can now add your expense to a project. I've attached a screenshot for your visual reference. 

With regards to tracking your profitability by location, you can turn on the location tracking option. This feature helps you see and trace the payments for one location and deposit them as a group. 

Once you're all set, you'll want to run your reports regularly to check if everything is accurate.

Let me know in your comment if you have other follow-up questions about projects in QBO. You're always welcome in the Community space. Have a good one!