I spoke with Mr. Saunders at OTC.  Seems all they want is a specific reference to the Oklahoma Statute when the code "99" is used as well as how the amount was determined.  I explained the tax program had generated a statement that said "Bonus Depreciation Adjustment" and the amount.  He looked at the return in question and said no statement was received in the e-file they received.  So that may have helped had they gotten it.  He suggested attaching a .pdf file with the explanation.  The statute is Okla Stat Title 68 Section 2358.6A.  They want the reference to the statute and an explanation that federal depreciation was "x" dollars, and Ok depreciation is "y" dollars, with the difference being the amount on schedule A.  Not liking the idea of having to generate a .pdf for every client with this issue, I then asked him if it was mandatory to take the 100% depreciation and he said no.  I further asked him if we could take 80% same as on the federal so there is no federal to state difference and he stated that was perfectly acceptable.  This is my plan on all returns going forward to avoid not only this issue, but to also avoid any federal to state difference on any potential recapture if an asset is sold before it is fully depreciated on the Federal return.  Hope this is helpful.