仕事は年末年始に関係なく　Work regardless of the holiday season

今年最後？の仕事は年末の掃除中にいただきました。外国人の入国に関するものですが、この年末年始の時期には納期が頭痛の種になります。
I have got the last(?) translation work in this year amid the year-end cleaning, which is about the immigration of foreigners. The delivery time becomes a problem around this time of the year-end and new-year.