Treatment of accumulated depreciation?

Not quite sure what you are asking here but I'll answer what I think is the question. If you were looking for something different, please post again and clarify your question.

The adjustment to record depreciation is:

Debit Depreciation Expense
Credit Accumulated Depreciation

Depreciation Expense is found on the Income Statement. Accumulated Depreciation is found on the Balance Sheet under the Fixed Asset section. The account credited monthly for depreciation until the allowed depreciation per asset is met, meaning the account grows over time. Another way to say this is: the depreciation that has taken place on a particular asset up to the present time. When you subtract accumulated depreciation from an asset, you come up with the net book value of the asset.