Consumables and products used in your services
Supplies are used directly in your services for your customers or patients 💉. They are not equipment, which is a working tool used in a general way for your services (not for a specific service) and intended to last. A supply is a single-use consumable:
Doctor: paper for examination table, pharmacy 💊...
Nurse: plasters 🩹, syringe, pharmacy, compress...
Dentist: products for making crowns or aligners...
These supplies can be re-invoiced to the customer or included in the service, they are in all cases fully deductible. If the invoice is sent directly to your customer, but you pay it (example of a lawyer with a court office voucher), then it is a disbursement (which the customer then reimburses to you).
💡 Any incidental costs (e.g. transport costs for delivery of the supply) also fall into this category. We say that the accessory follows the principal.