When you are changing the Activity setting between Billable ⟷ Non-billable, resources assigned to that Activity will be affected in the following way, depending on the direction:Billable Activity ➔ Non-billable ActivityWhen making the change, the following dialogues will be shown to you:If you click OK, the settings for the Resources assigned to this activity will be changed:PeopleBill Rates will be changed to 0 and won't be editableMaterialsClient Rates will be changed to 0 and won't be editableOther CostsAll Costs will be changed to Non-billable and this setting won't be editableLearn more about Non-billable Activities.Non-billable Activity ➔ Billable ActivityWhen making the change, the following dialogues will be shown to you:If you click OK, the settings for the Resources assigned to this activity will be changed:PeopleBill Rates will be changed to the default values for the Role (as per the Resource section settings)MaterialsClient Rateswill be changed to the default values (as per the Resource section settings)Other CostsAll Costs will be changed to the default Billable/Non-billable setting for the Cost (as per the Resource section settings)