Hi Mads_Frost,
Making sure you input and track your payroll information correctly is important for all businesses. I can definitely point you in the right direction for this.
QuickBooks Desktop's payroll add-on makes it easy to add commissions to employees pay. If you have questions on how to use the program or have technical issues we can provide you support. To ensure you are using the correct accounts and method to bill your payroll commission, I'd advise reaching out to your accountant. If you don't have an accountant you are working with currently we have you covered. You can find one in your area by going to our find an accountant page.
Once your accountant let's you know if it should bill it to your client or not, then we can help you with entering them into your QuickBooks Desktop account.
Have a great one!