How do I set up Childcare vouchers for salary sacrifice??

Welcome to the Community forum, @jan-dorling.

Currently, QuickBooks doesn't support childcare voucher. For the meantime, you can create a Pre-Tax deduction for you to show the item on the employee's payroll.

To set up a deduction category, here's what you'll need to do;

1. Choose Payroll Settings, then Deduction Categories.
2. To add a new deduction category, select Add. There will already be two deduction categories for you (Pre-Tax Deduction and Post-Tax Deduction). You can edit any of these by selecting the name of the deduction category.
3. Enter a name for the deduction category.
4. Select whether it will be a pre tax or post tax deduction.
5. Add an external ID and select the NMW/NLW Calculation Impact as required.
6. Hit Save.

Once done, you can now assign the deduction to your employees. 

Keep me posted if you have any additional questions, as I'm always here to help. Take care.