To Change Nationality to Indonesian make sure you have met these requirements:

1. You have resided in Indonesia for at least 5 consecutive years or 10 consecutive years by the time you apply for the Indonesian citizenship
2. You are at least 18 years old, or if you are under 18 years old, you have to be married
3. You are mentally and physically healthy
4. You never commit to any crime that makes you being prisoned for 1 year or more
5. You don’t have any other citizenship because Indonesia doesn’t admit a dual citizenship. So, if you are registered as a citizen of any other nationality, you need to prepare yourself to release your former citizenship.
6. You are able to speak Bahasa Indonesia/Indonesian language
7. You acknowledge Pancasila and Undang-Undang Dasar Negara Republik Indonesia Year 1945
8. You have a fixed income, or you are employed to a job
9. You agree to pay the citizenship fee

If you are getting married to an Indonesian, you just have to qualify for the requirements number 2, 5, and 9. Requirements: 

• The legalized photocopy of the birth certificate which has been translated into Indonesian
• Pictures of the passport
• Photocopy of SKTT or KTP OA that have been legalized
• Legalized photocopy of the marriage certificate/marriage book
• A letter from the Immigration office stating that you have stayed for 5 consecutive years or 10 non-consecutive years in Indonesia
• The Police Certificate of Good Conduct (SKCK) from the police region office (POLDA)
• The letter from the applicant’s country embassy stating that the applicant will release its former citizenship after gaining Indonesian citizenship
• A written statement from the applicant stating that the applicant will be loyal to the Republic of Indonesia, Pancasila, and Undang-Undang Dasar Negara Republik Indonesia year 1945.

Time : 3 months once the documents completed and only the president would decide whether your application is accepted or not. If you are accepted as the Indonesian citizen, you must be sworn.