政府採購法（下稱採購法）施行後通說均認已「法律明定」採取「雙階理論」，亦即以採購契約是否成立為基準，契約成立前認為係公法關係，契約成立後認為係私法關係。因此發生在契約成立前之所有爭議以及停權處分所生爭議，依異議、申訴及行政訴訟程序來處理。而採購契約成立後之履約爭議，則依採購法第八十五條之一項採購申訴審議委員會申請調解或依傳統之民事訴訟、仲裁解決爭議。在此立法架構下，政府採購第三十一條第二項規定列舉八種事由，投標廠商如有各該事由發生時，招標機關即可沒收押標金，如已發還者則予以追繳。本條在實務運作上發生該沒收押標金行為法律性質究屬公法或私法定性之疑義，行政法院之判決曾有不同之見解，但在最高行政法院97年作成決議之後實務即以首開雙階理論為依據視採購契約是否成立來判斷其法律性質之公私法屬性。然而就沒收追繳之法律性質仍不斷發生疑義，諸如：沒收押標金行為是否具有裁罰性？抑或僅具管制性？有無行政罰法之適用？有無時效之限制？如有，時效係應適用行政程序法抑或行政罰法？起算點又如何認定？諸多疑義仍待釐清。本文即以採購法第三十一條之「沒收」與「追繳」押標金為中心探討其法律屬性及其追繳時效之適用。

Since Government Procurement Act (hereinafter referred to as GPA) was implemented, it has been commonly agreed that the 'two level theory' is adopted by the law. That is, on the basis of award of procurement contract, before the contract is awarded, it is considered public law relationship; after the contract is awarded, it is considered private law relationship. Therefore, all controversies occur prior to award of contract are to be addressed in accordance with the opposition, pleadings, and administrative proceedings. Those occur after award of contract are to be conciliated by the complaint review board for government procurement or addressed by conventional civil proceedings or arbitration, as stipulated in Article 85 of GPA. Under the current legal structure, Article 31, Paragraph 2 of GPA enumerates eight circumstances. If any of the circumstances enumerated occur to the tenderer, the procuring entity can withdraw the bid bond deposited. If the bid bond has been returned, it can be recovered. Some questions had been raised when this Article was practically implemented, i.e. whether the act of withdrawing the bid bond belongs to public or private law relationship. The judgements by the Administrative Court reflected different interpretations. However, after the Supreme Administrative Court reached an agreement in 2008, practice started to, according to the 'two level theory', decide whether the legal characteristics belong to public or private nature, based on award of contract. However, there exist doubts regarding the legal characteristics of bid bond withdrawal and recovery. For example, is the act of withdrawing the bid bond embedded with penalty, or only the regulatory administrative measures? Is there any appropriation of the administrative penalty? Is there any statute of limitations ? If yes, does the limitation adopt Administrative Procedure Act or Administrative Penalty Act? How do we determine the starting point? Substantial doubts are still to be clarified. This article, centred around 'withdrawing' and `recovering' the bid bond in Article 31 of GPA, investigates its legal characteristics and the appropriation of the time-based limitation of pursuing.