僕が英訳するとしたら
Japan GAAP allows simpler accouting procedures on preparing quarterly statements compared with year-end regarding taxation and depreciation/amrotisation for fixed assets.
としか表現すると思います。
While measurements in both annual and interim financial reports
are often based on reasonable estimates, the preparation of
interim financial reports generally will require a greater use of
estimation methods than annual financial reports.
基準も背景も異なるのでもちろん単純比較はできませんが、
ここでの "a greater use of estimation methods" のほうが、
「簡便法」 よりも趣旨は明快ですよね。