When foreign dividends are below £500 there is an option to report this on page TR3 rather than completing foreign pages.
However, when that income has suffered overseas tax and the gross income is under £500 if one choses to report this on page TR3, although the software does show the net income and overseas tax credit on page TR3, the tax calculation itself treats the foreign tax as a deduction not a tax credit. Therefore one has to complete full foreign pages to obtain the benefit of foreign tax credit relief rather than as a deduction