What does Reporting Status mean?
Most ETFs are domiciled outside the UK - as such they are often treated as offshore investments for UK taxpayers.
Investors will pay income tax on any dividends that are paid by the ETF but unless an offshore ETF has UK reporting status for the entire period that the investor holds it, any gain on that ETF will be taxed as income instead of capital gains. This could subject the investor to significantly higher levels of taxation. Tax is complex and depends on your circumstances - for more information consult a tax accountant.