I have a new to QBO Client who began to use Projects on May 1, 2019. Is there a way for them to return to their January- April expenses and payroll, and assign these costs to specific Projects? How would I make that happen?
You can assign projects to new payroll going forward by using timesheets that feed into your payroll, however, moving the existing payroll transactions will need a Journal Entry instead. We currently don't have the ability to move existing payroll transactions into a project.
I've got a few resources here to help clarify further.
This article includes a section on calculating labor costs that might be helpful when creating the figures for your Journal Entry so you can move those expenses into a project.
This is an FAQ article about projects in general, however, has this specific section for entering your historical expenses, invoices into a project that was created after the transactions.
I hope this helps.