This is going to be really dicey and may put you at legal risk. I would not do anything substantial without talking to a professional who would defend you if you are audited.
First off, if you are a W-2 employee of the nonprofit, you cannot deduct any work related expenses because that deduction was eliminated for all W-2 employees in the 2018 tax reform.
Now, let us consider whether you could deduct your costs as a donation to the nonprofit organization. This is technically allowed regardless of whether you are an employee. You can deduct your out-of-pocket costs incurred while providing service to the charity or nonprofit. This could include office supplies, stamps, and other items that you buy for use of the charity. It might conceivably extend to the cost of running the home office, although I have not specifically seen this treated in the IRS instructions. The problem is that you cannot take a deduction for the use of your property, or for donation of a partial ownership interest, you can only take a deduction for the donation of the full value of some thing. In other words, you can only take a deduction if the thing that you donate becomes the charity‘s property, or is consumed in the performance of the service.
For example, if you lend a computer to the charity for their office, or use your personal computer in your home office, but you retain ownership, you cannot take any deduction, even though the computer undergoes wear and tear and loses value in the process.
That would mean that you might be allowed to deduct utilities that you spend in performing service for a nonprofit, but you can’t deduct depreciation, which would normally be included in the home office deduction.
Your legal risk is that you are an officer of the charity. The IRS takes a very dim view of self-dealing, or of using the charity for your own financial benefit. This not only can raise audit concerns for you, but it can endanger the exempt status of the organization.
Without advice from an experienced professional, the farthest I would go is to suggest that you can take a deduction for office supplies and other things that you buy that are either converted entirely to the ownership of the charity or that are consumed in the process of performing service for the charity, such as printer paper and stamps. And, I would get a letter acknowledging your donation that is signed by another officer of the charity attesting to the fact that you did indeed pay for supplies out of pocket that were consumed in performing services for the charity. Having a second person attest to your donation of these items may help you avoid a charge of self-dealing if audited.
An experienced tax professional may have a different opinion, or may have other suggestions on how to protect yourself from possible future liability.
