I am unable to tag expenses or assign them to a customer. The tag toggle is toggled on both in the categorize screen and in my settings. I need to assign expense to job.

The billable expense feature in QuickBooks Online (QBO) should be turned on to assign an expense to a customer, Tito.

Please note that this feature is available exclusively in the Plus and Advanced plans. If you're not on one of these plans and wish to access this feature, you may consider upgrading your subscription.

If you are currently using the said plans, here's how you can turn the feature on:

1. Go to the Gear icon, then select Account and settings.
2. Click on the Expenses tab.
3. Select Edit from the Bills and expenses section.
4. Turn on the following:
   • Show Items table on expense and purchase forms
   • Track expenses and items by customer.
   • Make expenses and items billable.
5. (Optional) Set up the following:
   • Markup rate
   • Billable expense tracking
   • Sales tax charge
6. Set bill payment terms.
7. Select Save, then Done.
   

After turning on the feature, here's how to assign an expense to a customer:

1. Select + New.
2. Choose Expense.
3. Complete all the necessary information.
4. Tick the Billable checkbox.
5. In the Customer column, select the customer you want to bill.
6. Select Save and close.

For more information, please visit this article: Enter a billable expense.

Please don't be confused by the tags, as they are used in two ways: to run reports and search transactions.

You mentioned assigning an expense to a job; are you referring to creating an expense for a project? If so, please know that you can create an expense directly within the project or create an expense transaction and then select the project as the payee.

I'd like to introduce you to the  QuickBooks Live Expert Assisted team. They are a group of experienced experts who can help you manage your financial operations to better meet your business needs.

After assigning a customer to an expense, you can use this helpful resource to guide you in linking a billable expense to your customer's invoice: Billable expenses (Add billable expenses to invoices).

If you need further assistance, feel free to return to this thread and leave your queries below. Have a great day!