This arises because the tax system of different income tax personal allowances, dividend allowances, savings rates has become more complicated rather than getting simpler!
These anomalies only arise in certain limited circumstances depending on the combination of dividends, interest and other income. We will ensure that tax returns are correct, as you would expect however in specific scenarios tax returns will have to be filed manually, rather than online. It is therefore more important than ever to be getting returns done as soon as possible.