Can a CPA letter reduce the expense factor on a business bank statement loan, and which investors accept one?

A CPA letter can indeed help reduce the presumed expense ratio applied to business bank statement income, but this benefit isn't universal—it depends on the specific investor's guidelines, and where allowed, it typically requires the CPA to formally attest to a lower expense factor than the standard default. Under standard business bank statement programs, lenders generally apply a flat expense ratio (often 50%) against deposits to estimate qualifying income, unless the borrower documents a lower actual expense ratio. A signed CPA letter, prepared by a licensed, independent accountant familiar with the business, can be used to support and justify a reduced expense factor, which increases usable qualifying income compared to the default assumption. That said, acceptance of this practice varies significantly by investor. Some non-QM investors, such as Verus, permit a CPA-prepared letter to override the standard expense ratio, provided the letter meets specific documentation and licensing requirements (Verus, Selling Guide p.12). Other investors may not allow any adjustment below their fixed default ratio, regardless of third-party certification. Because policies differ, borrowers and originators should confirm with the specific investor whether a CPA letter is accepted, what qualifications the CPA must meet, and whether there's a minimum expense floor even when a lower ratio is documented.