第三条の十の二（障害厚生年金等に関する事務の特例）
Article 3-10-2Special Provisions on Administrative Functions Connected with Disability Employees' Pensions and Survivors' Employees' Pensions
Where a beneficiary of a disability employees' pension and disability allowance has no insured period relating to the insured category (meaning the insured category prescribed in Article 15 of the Act; the same applies hereinafter) on the day of initial examination for the disability by the month that includes the day of disability assessment for the disability, the affairs relating to the payment of that disability employees' pension and disability allowance are to be performed by the persons specified in each item of Article 2-5, paragraph (1) of the Act, in accordance with the insured category specified in each of the following items for the case listed in that item.
where there has been a change in the insured category in the month that includes the day of initial examination for the disability (excluding the case listed in the following item): the insured category after the change (where there has been a change in the insured category two or more times, the last insured category);
where the month that includes the day of initial examination for the disability is an insured period under the National Pension (excluding the insured period under the National Pension as a category 2 insured person prescribed in Article 7, paragraph (1), item (ii) of the National Pension Act (referred to as the "period as a category 2 insured person" in Article 3-12, item (ii))): the insured category relating to the insured period that the beneficiary has.
当該障害に係る初診日の属する月が国民年金の被保険者期間（国民年金法第七条第一項第二号に規定する第二号被保険者としての国民年金の被保険者期間（第三条の十二第二号において「第二号被保険者期間」という。）を除く。）である場合 当該受給権者が有する被保険者期間に係る被保険者の種別
定義第三条の十の二第一項
法第十五条に規定する被保険者の種別
わかりやすく言うと
厚生年金保険の被保険者が第一号から第四号のどれに当たるかの区別です。第二号は国家公務員共済組合の組合員、第三号は地方公務員共済組合の組合員、第四号は私立学校教職員共済制度の加入者、第一号はそれ以外の被保険者です（厚生年金保険法第十五条）。
略称規定第三条の十の二第一項第二号・この規定及び第三条の十二第一項第二号の中だけ
当該障害に係る初診日の属する月が国民年金の被保険者期間（国民年金法第七条第一項第二号に規定する第二号被保険者としての国民年金の被保険者期間（第三条の十二第二号において「第二号被保険者期間」という。）を除く。）である場合 当該受給権者が有す…
わかりやすく言うと
国民年金の第二号被保険者、つまり厚生年金保険の被保険者としての国民年金の被保険者期間のことです（国民年金法第七条第一項第二号）。