Invoicing for direct project expenses

Is there any way to separate direct reimbursement for project expenses (e.g. subscriptions I took out for research or practical purposes out of pocket on a temporary basis, with agreement in advance from the buyer that they would be subsequently reimbursed when I invoice them as part of the project) from my own time/labour costs that I'm mainly invoicing for, in terms of differentiating them for VAT and PPH fees?