You’re right that you may need to pay tax on your investments, but this depends on a number of different factors.
Arguably the most prominent will be the type of account you’re investing in as some accounts can act as a ‘wrapper’, offering different forms of tax benefits or relief on the assets held within it. At the moment the accounts available with tickr are ISAs (Individual Savings Account) and GIAs (General Investment Account).
An ISA is a tax-free savings account and all UK tax residents are entitled to an annual ISA allowance. The allowance for the 2019-20 tax year is £20,000 (but this could change in future tax years). This means you can invest up to the ISA allowance in an ISA without paying any tax - so there’s nothing you need to do if investing in an ISA.
A GIA on the other hand is not a ‘tax-wrapper’. So any investments held in this type of account are subject to tax. There are different types of tax which may be applicable (such as, but not limited to, Capital Gains Tax and Dividend Tax) and these can be triggered at different times due to different actions/transactions. Usually you can pay them annually (e.g. through your tax return) or on an ad-hoc basis.
The different types of tax can also be different rates to each other, and different rates depending on whether you’re a Basic rate, Higher rate or Additional Rate tax payer. For many types of tax you can also have a ‘Personal Allowance’, which can differ between the different types of tax and the tax band you fall within.
It’s worth noting that they are other types of accounts and investment vehicles out there which can offer different forms of tax benefits and relief.
I hope this helps but as ever please get in touch if you have any more questions.