(for purposes of the $40,000 non-farm income limitation to be eligible to claim the tax exemption for a farm residence, homeowner may defer W-2 income in an amount which lowers the off-farm income to less than $40,000, can offset W-2 non-farm income with Schedule C or D non-farm losses to reduce the net non-farm income, and can offset Schedule C income so that the resulting total net of non-farm income is less than $40,000).