Eddy, ask the accountant what the taxable profit from the business is. That's the figure that needs to be over £18,600.
I believe right now, the accountant is taking £8,940 of expenses off the profit, meaning your wife will not be able to sponsor your visa. If this is the case, she does NOT want to take this allowance. If she pays tax on that £8,940, you will meet the requirement.
Very key - what was the business's taxable profit between April 6, 2015 and April 5, 2016? This is the number you care about.