Why the returns are the problem, not the proof
A profitable business run by a competent accountant is supposed to show less taxable income. Depreciation, equipment purchases, vehicle and home-office deductions and retirement contributions all reduce the number at the bottom of the return. The owner experiences a good year; the return reports a modest one.
Agency underwriting reads that bottom number. So the better the tax planning, the worse the file looks, which is the opposite of how the owner understands their own business.
What else can evidence income
Deposits into a business or personal account over a period can evidence revenue directly. A profit-and-loss statement prepared by a CPA can carry a file. For a borrower whose wealth sits in accounts rather than in a paycheque, a documented asset position can serve instead of an income stream.
These are different products with different documentation, not loopholes. A bank statement loan assembles the deposit history into qualifying income; asset depletion converts a documented asset position into one.
Who this actually changes the answer for
The owner five or more years in with healthy balances and a lean return. The commission earner with no W-2 anywhere and income that swings by month. The person eighteen months out of a salaried job whose business is growing but who cannot yet show the standard history.
All three get told no by a process that only reads returns, and all three are ordinary files somewhere else.
What to do instead of waiting
The common cost of this myth is time. People delay a purchase by a year or two to build a filing history they may not need, and buy later in a market they did not choose.
Send what you have (the business, roughly how it banks, and what you are trying to buy), before assuming the answer. Eligibility and terms vary by scenario and by lender guidelines; nothing here is a commitment to lend.