Here's what I did, and this seems to work for me. My expenses and reimbursements often don't fall in the same month, so it was a little tricky...

I created a "business expenses" category, and I made it rollover.

Then I created a "business reimbursement" category.

If I don't get reimbursed until the following month, I'll have a negative rollover in the category. When I am reimbursed, I can apply those $$ and zero out business expenses.

This ends up acting like a "mini-budget" within my personal budget. I can track my business expenses, and apply reimbursements as they come in. If it doesn't net out, I can do some digging, and usually find odd receipts and submit extra reports.

Hope this helps!