Hello, PabloT.

I understand you are trying to create billable expenses in QuickBooks Simple Start. However, I regret to inform you that this feature is unavailable in the Simple Start product. You cannot associate expenses with specific customers or projects and mark them as billable in Simple Start, as this is a product limitation. However, other QuickBooks versions, such as Essentials, Plus, and Advanced, offer this functionality. If you need to manage billable expenses, consider upgrading to one of these editions or exploring other options. 
 

To upgrade your subscription, here's how:

1. Sign in to QuickBooks Online as a primary or company admin.
2. Select Gear icon.
3. Under Profile and choose the Subscriptions & billing tab.
4. Make sure your payment info is up to date.
5. In the QuickBooks Online section, select Upgrade your plan.
6. Review the available plans and then select Choose plan for Essentials.
7. Follow the on-screen steps to upgrade your plan.

You can also check for third-party apps that sync with QuickBooks Simple Start by visiting the QuickBooks App Store. This platform offers a wide range of apps that integrate with QuickBooks and help you manage various aspects of your business. You can browse the app store by category, such as billable expenses, invoicing, time tracking, inventory management, etc. Choose the app that best suits your business needs, follow the instructions to set it up, and start syncing data with QuickBooks Simple Start. 

You're always welcome to reply to this thread if you have other questions or concerns about billable expenses or your subscription. Take care and have a nice day ahead.