I have no idea about whether or not you can marry. Why don’t you ask your taiwanes boyfriend to find out?? I am surprised he hasn’t since you are actually coming to Taiwan to marry him.[/quote]
[color=#FF4080]Maybe, more important question is how to change visa after the marriage… 
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Here are some useful threads on getting married in Taiwan and on applying for a Joining Family Residence Visa (JFRV) after you get married.
[url=Getting Married in Taiwan Married in Taiwan[/url]
When I got married I used this thread for guidance: Getting married and applying for JFRV
Also, this entire part of the forum is devoted to all things to do with getting married in Taiwan: Marriage
Read through the posts above, and it would be better to post threads on marriage in the marriage section where more people with the same questions (and answers!) will be able to help you.
Here is what I did, but remember that each country has some differences (Your boyfriend should really go down to the local National Immigration Office to get all the information he needs to help you with this, as some things can vary from country to country and rules can change), but bear in mind I got married in February 2007. In Taiwan, a lot can change in three and a half years!
To get Married:
- Apply for a “single certificate” from your home country proving you are unmarried. (Which needs to be translated into Chinese and verified by the Taiwanese consulate/Economic affairs office in your country.)
- Copies and originals of you and your spouse’s IDs (passport for foreigners)
- Copies of your two witnesses IDs (or passports for foreigners)
- You and your spouses name chops.
Once you have all these documents ready you will need to make an appointment with the court in your boyfriends area to get married.
That’s the easy part. Once married you will want to apply for a Joining Family Residence Visa (JFRV). So, after you get married and you have all your marriage certificates, you will need to go with your new husband to the Household Registration Office where his family book is registered. There you register your marriage into household registration and you are officially in his family book.
To apply for the JFRV you will need the following:
- Police clearance certificate from your home country. (Certified by your country’s department of foreign affairs, and authenticated by the Taiwanese economic/trade/consular office in your country, and translated into Chinese.)
- Taiwanese marriage certificate (that you got the day you were married)
- Proof that your marriage is registered in your home country. (This document also needs to be authenticated and translated in the same way as described above for the Police Clearance Certificate.)
- passport
- An application form
- ID photos (passport size)
- Household registration
- A health certificate done at a hospital in Taiwan accepted by NIA
- They also asked me for a Taiwanese Police Record Clearance (done in a few days at the Foreign Affairs Police).
- NT$1000 for a JFRV valid for one year. Takes about two weeks to do, but mine was ready in eight days.
That’s about all I can remember. I hope it helps. Good luck!
Edit: As far as I know you can get married on a 30 day visa, provided you have all the documentation (authenticated, translated and verified) ready.