Somewhere between the first paid partnership and the first five-figure deal, someone will tell you that you need an LLC. Need is the wrong word. You can run a fully legitimate brand business without one, and the reasons to eventually form one have almost nothing to do with the tax bill.
You can invoice brands without any LLC
The default business structure in America is the sole proprietorship, and it requires no filing at all. You can sign brand contracts, invoice, collect payment, deduct business expenses, and file Schedule C under your own name from day one. Taxes are identical either way: a single-member LLC is disregarded by the IRS, so LLC or not, the same Schedule C, the same income tax, and the same 15.3% self-employment tax on profit over $400 apply. Anyone selling an LLC as a tax loophole for your brand income is selling paperwork. What you should do immediately, LLC or not, is open a separate business bank account and, if you want to keep your Social Security number off brand paperwork, get a free EIN from the IRS to hand out on W-9 forms instead.
Separation from his contracts, his image, and his risk
The real case for an LLC in an athlete household is separation, in three directions. Liability: if a sponsored post, an event, or a product collaboration draws a lawsuit, a properly maintained LLC helps shield personal assets, which in your household are substantial. Identity: an LLC lets brands contract with and pay your company, keeping your personal name and his off the paperwork, useful when your last name alone invites inflated pricing and public attention. And finances: a business entity with its own account draws a bright line between your business, the household's money, and his career earnings, which keeps bookkeeping clean, simplifies things if his team or business managers handle the rest of the household, and preserves clarity that matters in prenup, estate, and planning conversations. The costs are state filing and annual fees, which vary widely by state, plus the discipline of never mixing business and personal spending, because commingling is how courts disregard the shield.
The upgrade path when the business earns its keep
A sensible sequence: sole proprietor with a separate bank account and an EIN while the income is getting established; form the LLC when deals are recurring, contracts are getting bigger, or a lawyer looks at your exposure and says it is time. Later still, if net profit becomes consistently large, the LLC can elect S corporation status with Form 2553, putting you on payroll and potentially trimming self-employment tax, an option worth professional modeling rather than a default. Form the entity in the state where you actually live and operate; out-of-state LLCs from famous low-tax states usually add cost and registration burdens without saving a resident anything.