"In Turbo Tax Business, how is the accounting income calculated for Form 1041?"
I presume you are referring to trust accounting income as shown on the Trust Accounting Income Smart Worksheet on the 1041 in TurboTax Business.
In that event, then generally, the trust accounting income displayed represents all income (including tax-exempt income) less deductions (excluding the trust exemption) plus any capital gain that you have allocated to income in the program (note that capital gain would ordinarily be excluded from the calculation).
