How are people handling reimbursements?

We frequently have reimbursable expenses where we spend money in one month but don't get the reimbursement until the following month. We have tried creating a reimbursements category that we assign this spend to and then when we get the money back, we can assign the inflow to offset the spending.

The problem becomes that categories won't carry a negative balance from one month to the next so if the original spend and the repayment are in different months we can't just let it roll over. It works OK if all the spend is on a credit card since that will allow negative spend to carry over to the next month but if any of the spending was cash then it becomes an issue.

Has anyone come up with a solution that works well in this situation?