Where a claim for a refund is made under the provisions of Article 141, paragraph (1) or (4) (Claim by an Heir to Be Issued a Refund Based on Carryback of Net Loss) of the Act, if there are two or more heirs, the claim for a refund under the provisions of Article 142, paragraph (1) (Procedures for Issuing Refunds Based on Carryback of Net Loss) of the Act pertaining to that claim must be submitted by each heir in a single document jointly signed; provided, however, that this does not preclude each heir from submitting it separately with the names of the other heirs appended.
法第百四十一条第一項又は第四項（相続人等の純損失の繰戻しによる還付の請求）の規定による還付の請求をする場合において、相続人が二人以上あるときは、当該請求に係る法第百四十二条第一項（純損失の繰戻しによる還付の手続等）の規定による還付請求書は、各相続人が連署による一の書面で提出しなければならない。ただし、他の相続人の氏名を附記して各別に提出することを妨げない。
An heir who has submitted the claim for a refund referred to in the preceding paragraph by the method set out in the proviso to that paragraph must, without delay, notify the other heirs of the gist of the matters stated in that claim for a refund.
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heirmachine translation
「相続人」
An heir, including, wherever this Cabinet Order uses the word, a universal legatee (包括受遺者): a person to whom a will leaves all or a share of an estate as a whole, rather than particular property.
Defined inArticle 1, paragraph (3)· applies throughout the law