A LLC is a pass-through entity on taxes. The IRS will class it as a Sole Proprietorship (or Partnership if others own part of it) Look at a Federal form SS-4. Any deduction available as a individual is there as a LLC. The LLC does not prevent any deductions an individual would have.
It sounds like the first thing you need to do is FIRE the CPA.
The only way it makes sense to split the bonus payment across two years, is if the bracket changes for a large portion of it, or you expect far less taxable income next year.
Some people think that when they move to a higher tax bracket the rate changes for all of the income. That is not correct. The rate only changes for the amount that exceeds the cap of the previous bracket.
Federal Married filing jointly tax rates:
10% on taxable income from $0 to $17,850, plus
15% on taxable income over $17,850 to $72,500, plus
25% on taxable income over $72,500 to $146,400, plus
28% on taxable income over $146,400 to $223,050, plus
33% on taxable income over $223,050 to $398,350, plus
35% on taxable income over $398,350 to $450,000, plus
39.6% on taxable income over $450,000.
Say you are going to get a $50K bonus and you are in the 25% bracket rate making $126,500 (without the bonus) . On the bonus you'll pay 25% on the first $20K and 28% on the remaining $30K. 5K+8.4K or $13,400 in taxes.
If you split it into two payments of $25K
you'll pay 25% on the first $20K and 28% on the remaining $5K each year. 5K+1.4 K or $6,400 each year.
All of that work and you pay $12,800 instead of $13,400. You save $600 "IF" tax rates do not increase.
And I don't want to trust them to pay me the other 1/2 next year. I'd just as soon have it up front.