The deductibility of software or printers purchased is determined by who owns it.
Anytime a business purchases a printer or software in their name for the purposes of servicing clients or using for their own business, then they would receive the full deduction for that purchase. If that purchase is $2,500 or less, the company can expense it. If it is greater than $2,500, the company would capitalize the purchase. You would not break out a portion for the business and a portion for the client unless you both own the asset. If that is the case, you would deduct based on your portion of ownership, which should be in a written agreement signed by all parties.
There are companies which may charge a software fee to help cover the costs of the software when they are using it for client purposes. Such a fee would be added to your business income and can be deducted by the client on their taxes if it is for their business and not their personal use.
If the client owns the software and/or printers, they would be able to deduct the expense. There is no tax issue if they allow you access to the software and/or printer so that you can service them.
If the company is purchasing software and/or printers which they will sell to a customer, then that is considered inventory; which, depending on the state, may or may not be subject to sales tax.
