Answer
The best way to record unpaid leave in Lightning Payroll is through a custom leave balance. First create the balance at the company level, then link it to each relevant employee.
Step 1: Create the Custom Leave Balance
In the desktop app: Go to Company >> Leave Balance and use the add button to create a new leave balance. Set the following:
In the online (web/mobile) app: Go to Company >> Leave Balances and use the add button to create a new leave balance. Set the following:
- Name: Unpaid
- Treat As Overtime?: Ticked
- Pay At Zero Dollars?: Ticked
- No Balance/Accruals Required?: Ticked
The other options can be left at their defaults.

Step 2: Link the Balance to Employees
After creating the custom leave balance, link it to each relevant employee.
In the desktop app: Go to Employees >> Leave >> Custom Leave Accruals and add the Unpaid leave type there.
In the online (web/mobile) app: Go to Employees >> Leave >> Custom Leave Accruals and add the Unpaid leave type for the employee.
Step 3: Record Unpaid Leave in a Pay
In the desktop app: When editing a pay under Pays >> Edit Pays, open Edit Leave Taken in this Pay and select Unpaid as the leave type.
In the online (web/mobile) app: When editing a pay, select the Leave Taken tab and add a row using the Unpaid leave type.
Leave taken will default to the employee's base ordinary time pay rate. Because the leave balance is configured to pay at zero dollars, you should verify the hourly rate is set to zero before saving the unpaid leave row.
For more information on setting up custom leave types for RDOs, TOIL, and similar arrangements, see How Do I Add Additional or Custom Leave Types?