台灣人在中國大陸生活、工作或求學時，主要會接觸到三種證件：台胞證、居住證和定居證。這三種證件各有不同的功能與法律效力，適用於不同的需求與身份狀態。

首先，台胞證（台灣居民來往大陸通行證）是台灣居民進出中國大陸的基本證件，由中國大陸公安機關簽發。主要功能是作為出入境憑證，同時在大陸境內也可用於住宿登記、交通購票、銀行開戶等日常事務。台胞證分為一次性證和五年有效的卡式證，後者是目前最常見的類型，持證人無需額外申請簽注即可多次往返。值得注意的是，台胞證號碼的格式與大陸身份證不同，這可能導致某些線上服務無法直接識別，例如在註冊部分網路平台時可能遇到困難。

其次，居住證是為長期在大陸生活的台灣居民設計的身份證明文件。它的最大特點是提供一組18位數字的號碼，格式與大陸身份證完全相同，這使得持證人在辦理社會保險、銀行業務、教育醫療等事務時更加便利。申請居住證的條件包括已在大陸居住滿六個月，並具有合法穩定的就業、住所或就學證明。居住證的有效期通常為五年，到期可申請換發。需要特別說明的是，居住證並不改變持證人的台灣居民身份，也不會影響其在台灣的戶籍與權利，它純粹是為了方便台灣人在大陸長期生活而設立的實用性證件。

最後，定居證則是台灣居民申請大陸戶籍時必須取得的證件。這是一種涉及身份轉換的正式文件，申請人需符合特定條件，例如與大陸配偶結婚滿一定年限、直系親屬為大陸公民，或是符合人才引進等政策要求。取得定居證的台灣居民必須註銷台灣戶籍，正式成為大陸公民，並可申領大陸身份證。這一過程具有不可逆轉的特性，因此通常只有計劃長期在大陸定居、且確定放棄台灣身份的人才會申請。由於涉及法律與政治層面的敏感問題，建議在做出決定前充分諮詢專業人士的意見。

綜合來看，這三種證件滿足台灣人在大陸的不同需求：台胞證解決基本出入境問題，居住證提供長期生活的便利，而定居證則是身份轉換的最終步驟。大多數台灣人會根據自身情況選擇「台胞證+居住證」的組合，既能維持台灣身份，又能享受大陸的生活便利；只有極少數人會選擇申請定居證，這通常與家庭團聚或職業發展的長期規劃有關。在實際使用中，每種證件的功能與限制都值得仔細了解，以做出最符合個人需求的選擇。

台灣陸委會也表示根據兩岸條例第9條之1規定，若持有中國身分證、定居證跟護照，就會失去台灣人的身分，之後若入台需要透過申請通過才可。

When Taiwanese citizens live, work, or study in Mainland China, they typically encounter three types of identification documents: the Taiwan Compatriot Permit (台胞證), the Residence Permit (居住證), and the Settlement Permit (定居證). Each of these documents serves different functions and carries different legal implications, tailored to specific needs and identity statuses.

First, the Taiwan Compatriot Permit, officially called the Mainland Travel Permit for Taiwan Residents, is the primary document for Taiwanese citizens to enter and exit Mainland China. Issued by the public security authorities in China, it functions as both a travel document and a domestic ID substitute. Within China, it can be used for tasks such as hotel registration, purchasing transportation tickets, or opening a bank account. There are two main types: a single-entry paper permit and a card-format permit valid for five years—the latter being the most commonly used today. The card-format permit allows for multiple entries without the need for additional endorsements. However, it’s worth noting that the ID number format differs from that of a Mainland Chinese ID card, which can result in compatibility issues with some online platforms or services, such as difficulties registering on certain websites.

Second, the Residence Permit is an identification document specifically designed for Taiwanese citizens who intend to reside in Mainland China for an extended period. Its most notable feature is the issuance of an 18-digit number identical in format to a Chinese national ID, which significantly facilitates access to services such as social insurance, banking, education, and healthcare. To qualify, applicants must have resided in Mainland China for at least six months and provide proof of legal and stable employment, residence, or enrollment in an educational institution. The permit is typically valid for five years and can be renewed upon expiration. Importantly, the Residence Permit does not alter the holder’s Taiwanese citizenship status or affect their household registration and legal rights in Taiwan. It is purely a practical document to improve the convenience of long-term life in Mainland China.

Finally, the Settlement Permit is required for Taiwanese residents seeking to acquire official household registration (hukou) in Mainland China. This represents a legal change of status. Eligibility is limited to individuals who meet certain criteria—such as being married to a Mainland Chinese citizen for a specified number of years, having close relatives who are Chinese citizens, or qualifying under talent recruitment policies. Taiwanese individuals who obtain a Settlement Permit must renounce their household registration in Taiwan, thereby officially becoming citizens of Mainland China and qualifying for a Chinese Resident Identity Card. This process is irreversible, and as such, it is generally pursued only by those who plan to permanently reside in Mainland China and are willing to give up their Taiwanese nationality. Given the legal and political sensitivities involved, it is strongly advised to consult legal professionals before making such a decision.

In summary, these three documents serve different purposes for Taiwanese residents in Mainland China: the Taiwan Compatriot Permit covers basic entry and exit needs; the Residence Permit provides convenience for long-term living; and the Settlement Permit marks a full transition in legal identity. Most Taiwanese opt for a combination of the Compatriot Permit and Residence Permit, which allows them to maintain their Taiwanese citizenship while enjoying the practical benefits of life in China. Only a small number choose to apply for the Settlement Permit, usually driven by considerations such as family reunification or long-term career development.

The Taiwan Mainland Affairs Council (MAC) has also clarified that, according to Article 9-1 of the Act Governing Relations between the People of the Taiwan Area and the Mainland Area, any Taiwanese citizen who obtains a Chinese ID card, Settlement Permit, or passport will be deemed to have forfeited their Taiwanese status. If such individuals wish to re-enter Taiwan, they will be required to apply and obtain approval in advance.