Car 
Motorcycle I just moved to Taiwan. Can I drive on my International Driving Permit, and for how long?
Short answer
Yes, if your IDP comes from a country Taiwan has IDP reciprocity with, which is 176 of the 200 on the official table. The first 30 days need nothing else. After that you register it at a Motor Vehicles Office for NT$150, and it is good for one year at most, or less if your licence or residence permit runs out first. It is a bridge, not a licence, so use that year to exchange your licence or pass the exam.
Most people who arrive with an International Driving Permit (IDP) assume it works the way it did on their last holiday, as a piece of paper that lets you drive anywhere for a while. In Taiwan it does let you drive, but on a clock, and only if it comes from the right country. The rule fits in one article of the law, §55 of 道路交通安全規則, so here it is in full.
The first 30 days, nothing to do
If your IDP was issued by a country Taiwan has reciprocity with and it is still valid, you can drive here for up to 30 days without registering anything. Carry it together with your original licence and your passport. The IDP is a translation of your licence, not a replacement for it, and on its own it proves nothing.
That is also the whole answer for a tourist. A trip of under a month needs the IDP, the licence and the passport, and that is all.
After 30 days, register it, NT$150
Stay longer and the IDP has to be registered (簽證) at a Motor Vehicles Office (監理所 / 監理站). The fee is NT$150, set in the national fee table. Expect to bring the IDP, your original licence, your passport or ARC, a photo and the application form, which the office gives you.
Registered, it lets you drive for one year at most, and the year is cut short by whichever runs out first, your home licence, your IDP or your residence permit. Past that date you are not licensed to drive here at all, and being stopped then counts as driving without a licence, which is a fine of NT$6,000 to 24,000.
So the 30 days are not a grace period you can stretch. On day 31, an unregistered IDP is no longer enough.
Which countries count
§55 only accepts an IDP from a 互惠國, a country that does the same for Taiwan. The official reciprocity table records, country by country, whether each one honours a Taiwanese IDP, and Taiwan returns the favour.
The answer is yes for 176 of the 200 countries, states and territories on that table, and the exceptions are not the ones people expect. Vietnam, Myanmar, mainland China, Pakistan, Mongolia and Brazil are on the no side, and so are California, New York, Massachusetts and Oklahoma, because the United States is agreed state by state here too.
Pick your country in the checker and it shows both answers at once, whether your IDP works now and whether your licence can be exchanged later.
Japan is the exception, and it is not an IDP
A Japanese licence does not travel to Taiwan as an IDP. It travels with a Chinese translation issued for the 日本台灣交流協會 and made by JAF, which costs ¥7,000 and has to be ordered in Japan before you leave. With the licence, the translation and the passport you can drive here for one year from the day you enter, with no registration. After that year, you exchange it for a Taiwanese licence, and the same translation is what you hand over for the exchange.
It only covers what is printed on it
An IDP carries the vehicle classes of the licence behind it, nothing more. A car-only IDP does not cover a scooter, and that is the trap for anyone who arrives planning to ride. Most car licences elsewhere include no motorcycle entitlement, so the permit has none either, and a rental shop that hands you a scooter anyway is not making it legal.
This matters most for the workers who arrive by motorcycle-first routes. An IDP from Indonesia, Thailand or the Philippines is honoured here, but only for the classes it shows. An IDP from Vietnam or Myanmar is not honoured at all, so for those riders the exam is the only way onto the road.
What to do with the year
The IDP is a bridge, and it ends. Which way it leads depends on your country, and the checker tells you in one go.
If your licence can be exchanged, do not wait for the year to run down. The exchange can be done from the day after you arrive, as long as your residence permit is valid for six months or more, and it is a walk-in errand that costs NT$200. Here is exactly where to go and what to carry. Do it while your home licence is still valid, because an expired one cannot be exchanged.
If it cannot, start on the exam now rather than in month eleven. For a car, the self-study route needs a learner permit held for three months before the practical test, and exam slots are booked online from 30 days ahead, so starting late can leave you with no licence when the IDP year ends. For a scooter you clear the hazard perception test and a two-hour safety class before you can even book. The written part of both is drawn entirely from the free official question bank, which is what the app is built on. What the full route involves.
Rental companies can ask for more
Everything above is what the law allows. A rental company is free to set a stricter rule of its own, an age limit, a year of driving experience, or an IDP even where the law would not require one, so check with the company before you count on a car at the airport.