Whether it is a monthly transfer for the household, a card in your name on his account, or a lump sum after a new contract, the money moving from your athlete partner to you raises the same quiet question every year: do I owe tax on this? Here is the clean answer, in both the married and unmarried versions.
Married: transfers between spouses are a tax non-event
If you are married, money and property moving between you and your spouse is simply not a taxable event. You owe $0 of income tax on it, he gets no deduction for it, and no gift tax applies because of the unlimited marital deduction for spouses who are US citizens. The household transfer, the joint account, the car he bought in your name: none of it appears on any income tax return as income to you. He already paid income tax when he earned the money; moving it inside the marriage does not tax it again. One caveat worth knowing exists for a spouse who is not a US citizen: the marital deduction for gifts is not unlimited in that case, and an annual limit, adjusted each year, applies on the gift tax side, still his paperwork, never income to you.
Unmarried: gifts are not income, but the giver has rules
If you are not married, a genuine gift is still not income to you; the tax law excludes gifts from the recipient's income entirely, whatever the amount. The rules that do exist sit on his side. A giver can hand any one person up to the annual gift tax exclusion each year with no paperwork at all; the exact amount adjusts annually, so check the current figure. Above it, he files a gift tax return, Form 709, which usually just tracks the amount against his large lifetime exemption rather than creating tax due. Either way it is his filing, not yours, and nothing lands on your Form 1040.
The exception: pay for actual work
The picture changes the moment money is compensation instead of generosity. If you manage his brand partnerships, run his foundation, handle his scheduling, or work in his LLC and get paid for it, that money is earned income: taxable to you, reportable on a W-2 or a Schedule C depending on how you are engaged, and subject to payroll or self-employment tax. The same is true of appearance fees or brand deals paid to you directly by third parties; those are your business income, not gifts. Labels do not decide this, substance does: money for services is income no matter what the transfer memo says.
Keep it simple in practice: household support and gifts, no tax to you; payment for work, ordinary taxable income. When one transfer mixes both, split it, and put the working relationship on real payroll or a real contract so the line stays bright.