By Tim Sarson Politicians love to talk about the tax gap as a pain-free revenue-raiser, but there is a genuine difference between tax owed and what’s collected, mostly because the system is far too complicated, says Tim Sarson Last week the Shadow Chancellor Rachel Reeves summoned up an old favourite of British fiscal administration: the tax gap. Labour aims to deliver additional tax revenue of £5bn per year by the end of the next parliament by, amongst other things, putting more resources into HMRC and investing in technology. The tax gap has been a talking point long enough now to qualify fo…