There are no taxes to pay on any capital gains, interest from savings, dividend earned on any stocks or shares investment under TFSA account. Also any capital gains, interest, dividend that increases the value of your investment, will not affect your annual contribution limit. This is why TFSA is the best account to hold investment and allow it to grow tax free. TFSA is very popular amongst the young people because of its tax free nature. It allows young people to save up for a specific goals such as university course fees, marriage, brand new car, down payment for house or for a future child's education.
However, you need to be cautious of the TFSA contribution limit allowed each year. The contribution room allowance usually is the same amount each year except some years it changes. The government revises the contribution amount from time to time. If you happen to over contribute for a certain year, you could be charged penalty percentage for the over contribution amount. It doesn't matter how many TFSA account you opened in any number of banks, the added total of all your investment and savings in TFSA should not exceed the total allowed TFSA contribution amount.
Although you can see how much contribution room you are allowed using the CRA "My Account" feature, you should always have your own record of how much you contributed to your TFSA account. If you withdrew a certain amount during one of the years, you can recontribute the same withdrawn amount but on the next year. You can't do it in the current year, only with the exception that you still have enough contribution room and you don't over contribute .
The table below will show how much you can contribute so far starting from 2009, when this TFSA program first started:-
Year Annual Limit
2009 - $5000
2010 - $5000
2011 - $5000
2012 - $5000
2013 - $5500
2014 - $5500
2015 - $10000
2016 - $5500
2017 - $5500
2018 - $5500
2019 - $6000
2020 - $6000
(Total - $69500)
This means that if you have never contributed any money into your TFSA account, you can now contribute to the maximum of $69500 today. If you had been contributing some amount each year, you need to keep a record of how much you saved in your TFSA account and keep a check on the TFSA contribution room for current year.