You're changing from an expensed asset to a depreciable asset. It seems that requires a 3115. Read §1.446-1(e)(2)(ii)(d)(2). 

Additionally, a correction to require depreciation or amortization in lieu of a deduction for the cost of depreciable or amortizable assets that had been consistently treated as an expense in the year of purchase, or vice versa, is a change in method of accounting.