We are a nonprofit with grants from several sources. How can we allocate payroll expenses among several different expense accounts, one for each grant using QB Payroll?

You can create a different pay type for a specific employee and allocate the expense account in the payroll settings, @WebeRE. I know how to do this. I'll share it with you.

To distribute the $250 to Grant A, $250 to Grant B, and $500 to Grant C, manage three pay types. This way, you can allocate exact expense accounts for the different pay types inside the Payroll settings. Here's how to handle the payroll settings:

1. In the Gear icon, tick Payroll settings under YOUR COMPANY.
2. Scroll down until you reach Accounting and click the pencil option.
3. Hover the Wage expenses and select the pencil symbol again.

4. Choose Each employee's wages are posted to different types of accounts, then pick the exact expense accounts for each pay type.
5. If done, hit Save.

On the other hand, to track your funds inside QBO as a non-profit organization, you can check this article as a guide: Fund Accounting for non-profits in QuickBooks Online.

If queries and questions are still up in your mind, you're free to ask here again in the Community space. I'll be happy to assist you again. Have a good one.

@KayePe 

The OP's question is: "How can we allocate payroll expenses among several different expense accounts, one for each grant using QB Payroll?"

Did you answer the question? No, you did not. 

Did you even read the question? I doubt it.