To reinterate "the other 10% is taxable income *to the benefiting partner*" So there is no deduction here on the partner's personal return. In fact, it's exactly the opposite and is reported as taxable compensation by the business, that was paid to the partner. The fact the partner used it to pay for 10% of the cost for their personal use is irrelevant, and is not tax deductible on that partner's personal return.
