The official taxis in Tenerife are white, and you will see plenty of these around, especially in the busier larger resorts on Tenerife. From experience it is a good idea to ask the driver what the cost of the fare will be to where you are going before you get in the Taxi.
The white taxis have meters, and the fare will be on the meter. However it is still advisable to ask the driver first. With regard to tips it is standard to just round up the fare. So if your taxi ride is 9.50 Euros, it is acceptable to pay the driver 10 Euros.
If you are taking a taxi from your hotel, most staff on the reception desk will have a rough idea of the fare you should expect to pay, if they don’t know, ask them to find out for you. A lot of the good hotels have a Taxi tariff to popular destinations around the Island.
From my experience I once forgot to ask the driver about the fare upfront. My thoughts were elsewhere like getting to the airport on time. Once at the airport this particular driver came up with a higher price than was on the meter, in fact five Euros more. I am aware there is an airport supplement, and the last time I looked this was 1.65 Euros.
This is rare as the taxi drivers are normally o.k. However there are a few who will take advantage of the tourists, and charge a higher rate. When you reach your destination if you are suspicious of the fare, ask the driver for a written receipt, and make a note of his cab number.
There could be extra charges for a particular journey, such as night time charges, special events, baggage, or if you just flag a taxi down. It is best to find out or be in the know how much the fare is to where you are going. On the occasion I am referring to above, I had no idea if there were extra charges on top of what the meter was reading or the driver just decided to add an extra five Euros on.
So sort out the fare before you jump in!