What is the accounting journal entry for depreciation?

Depreciation a/c always debit as it is a expense a/c and particular asset account should be credit. For ex: depreciation on Building, then

Depreciation on buildings  Dr         xxx

  Building a/c                  Cr            xxx

Note : No depreciation on land.

Dr   Depreciation Ac   xxx

Cr       Asset Ac              xxx

For which of the asset you want to take the depreciation Cr that Asset, for example Vehicle, Machinery etc 

Depreciation Expense  (Dr.)

Accumulated Depreciation    (Cr.)

That's one effect. There is also taxes. They will be overpaid.

Depreciatin a/c Dr                ***

    TO Asset a/C                   ***

Depreciation a/c Dr

Asset a/c

Dr Depreciation(I/S)

Cr Acc.Depreciation

The basic journal entry for depreciation is to debit the Depreciation Expense account (which appears in the income statement) and credit the Accumulated Depreciation account (which appears in the balance sheet as a contra account that reduces the amount of fixed assets)