Brilliant, this is exactly what I was looking for. Right after IronMan's reply I started looking at the Sec 179 deduction instead. Primarily because Kentucky doesn't conform to Bonus Depreciation rules.

Publication 946 specifically says you can elect to deduct "all or part of an assets costs". Additionally it goes to say, "If you deduct only part of the cost of qualifying property as a section 179 deduction, you can generally depreciate the cost you do not deduct."

For those wondering, here's the difference in electing Bonus Depreciation vs Sec 179 in this example and why I'm going through all of this trouble in the first place for my client.

Federal Refund with Bonus Depreciation - $3,933

State Tax Liability with Bonus Depreciation - $2,190

Net Impact to Taxpayer - Refund of $1,743

Federal Refund with Sec 179 - $5,750

State Tax Liability with Sec 179 - $0

Net Impact to Taxpayer - Refund of $5,750

Difference - $4,007

There are two reason's why there are differences this large that I can see:

1.  Using Bonus Depreciation is reducing AGI to an amount that is impacting the potential of the Earned Income Credit and Child Tax Credit.

2. Kentucky doesn't conform with Bonus Depreciation rules.

If anyone sees something wrong with this approach or my reasoning please comment! I just want this information to be available to someone else that may have a client that fits a similar shape.