If you hold Portfolio+ within an ISA or a SIPP:
You do not have to pay income tax on any income or capital gains tax on any disposals.
If you hold Portfolio+ in a Fund & Share Account:
Income: Income received on the holdings (such as dividends and interest) will be subject to income tax. Income rolled up into your accumulation units is also taxable. If you are a higher rate taxpayer, you will be required to include this income on your personal tax return. If you are a basic rate taxpayer, it is likely that most tax due will be collected at source. If you are required to fill in a tax return, even as a basic rate taxpayer, you should include this information.
Capital gains tax: Capital gains tax may be due on any disposals. This will depend on the amount of gain, and whether or not you have disposed of any other chargeable assets in the same tax year. Disposals may include, but are not limited to: sales of units (both where you sell holdings, or sales to raise funds to settle fees), sales for the purpose of rebalancing the portfolio biannually, transfers to others and gifts.
You should note that the above is guidance only and you should seek specialist tax advice from an accountant or tax adviser if you are unclear. You are responsible for ensuring that you correctly report and pay tax on your income or gains.