That an article has appeared in the Daily Mail today claiming that flat taxes would help the poor should come as no surprise. That it is based on a piece of original research by the Joseph Rowntree Foundation however ought to raise at least the odd eyebrow.
In fact, man-bites-dog spin from the JRF notwithstanding, the flat tax is only half the story. What the JRF are also proposing is the creation of a negative income tax system to replace the extremely complicated existing system of tax credits. That sounds more like the bunch of Quakers we know.
Personally, of course, I would go further: most countries worldwide that have flat income tax rates also have significantly higher property taxes. By introducing these (LVT to be specific) at the same time you could significantly reduce the base income tax rate while capturing more wealth from the better off in a more economically efficient manner. But I’m repeating myself.