The Overseas Community Affairs Council (OCAC) in Taipei offers free Chinese learning workbooks to overseas Taiwanese. Each non-Taiwanese passport presented allows you to select 10 books. Remember to bring a passport for each child you are getting books for. Also bring a separate ID for yourself as you will need to leave it at the security desk.
The Overseas Community Affairs Council is located at 100, Taiwan, Taipei City, Zhongzheng District, Xuzhou Road, 5號. Their hours are 9am-12pm and 1.30-5.00pm from Monday to Friday. They are closed during lunch.
The OCAC library is on the 15th floor down the hall from the elevators. They offer textbooks and workbooks for all reading levels. I was able to get 10 books for myself, and my son and daughter. It was a bit much lugging 30 textbooks back home and definitely took up too much luggage space. If you plan on returning to Taipei often, I suggest making multiple trips to the OCAC and only getting the books at your child’s current learning level. Here are some photos of the books.