Supplementary Provisions, Article 4Transitional Measures Concerning Periods to Which Revenue and Expenses Associated with Contracts for Construction Work Are Attributed
第四条（工事の請負に係る収入及び費用の帰属時期に関する経過措置）
Article 66 of the new Income Tax Act applies to construction work prescribed in paragraph (1) of that Article (other than transitional construction work) which an individual begins on or after January 1, 2009, and the provisions then in force continue to govern construction work prescribed in Article 66, paragraph (1) of the former Income Tax Act (including transitional construction work) which an individual began before that date.
新所得税法第六十六条の規定は、個人が平成二十一年一月一日以後に着手する同条第一項に規定する工事（経過措置工事を除く。）について適用し、個人が同日前に着手した旧所得税法第六十六条第一項に規定する工事（経過措置工事を含む。）については、なお従前の例による。
The term "transitional construction work" as used in the preceding paragraph means, in the case where an individual, in 2009, does not account, based on the construction progress criteria that Cabinet Order prescribes as referred to in Article 66, paragraph (2) of the new Income Tax Act, for any construction work that the individual is contracted for (meaning construction work as prescribed in Article 66, paragraph (1) of the new Income Tax Act) and begins during that year (other than construction work whose object is delivered during that year; hereinafter referred to as "work begun" in this paragraph) that falls under the category of long-term, large-scale construction work as prescribed in paragraph (1) of that Article as of December 31 of that year (or as of the time of death, if the individual dies partway through the year) (other than work begun that falls under the category of long-term, large-scale construction work as prescribed in Article 66, paragraph (1) of the former Income Tax Act as of that day (or as of the time of death, if the individual dies partway through the year) and work begun that Cabinet Order specifies as having a low rate of progress), that work begun.
前項に規定する経過措置工事とは、平成二十一年において、個人が請負をする工事（新所得税法第六十六条第一項に規定する工事をいう。）で同年中に着手するもの（同年中にその目的物の引渡しが行われるものを除く。以下この項において「着手工事」という。）のうち同年十二月三十一日（年の中途において死亡した場合には、その死亡の時）において同条第一項に規定する長期大規模工事に該当するもの（同日（年の中途において死亡した場合には、その死亡の時）において旧所得税法第六十六条第一項に規定する長期大規模工事に該当するもの及びその進行の割合が低いものとして政令で定めるものを除く。）のいずれかについて同年において新所得税法第六十六条第二項に規定する政令で定める工事進行基準の方法により経理しない場合における当該着手工事をいう。