This is a common misunderstanding.

You need to understand Perspective. The service provider and the organization = 2.

The organization is supposed to acknowledge the value of professional services provided, as they can use this for proof of Support. Example: You do their taxes and would normally charge $800. It's the same as if someone donated $800 and then they hire you to do the taxes for that $800.

That is donation Value for the organization. That is not a Write off for you, unless you also Write ON the $800 as income. You would invoice them to show them your value, and credit back or discount that 100%, for your own business records. Now they have proof of support.

Someone should educate that organization so that they learn to State This Properly, and they learn to request what they need for their records without confusing everyone else with false guidance.