There's a feature called Billable Expenses in QuickBooks Online. David.
This will let you track all expenses you've made on behalf your customers or projects while the work is begin done.
When you purchase stock items, they are reported and increases your stock asset account. Once the item is sold and added to your sales transactions, the amount in the stock asset account is also reduced with the same amount.
I'll share the steps on how to activate and use the feature. Here's how:
- Go to the Gear or Settings ⚙ icon, then select Account and settings.
- Proceed to the Expenses tab.
- Click Edit ✎ under the Bills and expenses section
- Turn on the following:
- Show Items table on expense and purchase forms
- Track expenses and items by customer.
- Make expenses and items billable.
- Select Save.

Once done, you will see a Customer/Project column when creating expense transactions every time you buy stocks. Aside from that, you can also mark transactions as billable to the projects when you record them. Just check the Billable box if you want to add the transaction when creating invoices.

In terms of lowering a tangible asset, you can do that via a journal entry, we'd recommend speaking with an accountant for advice on that.
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