I have been an expat for the last 8 years so my UK tax info is obviously way out of date but it strikes me that this new process will be very time consuming for both the individual and the Inland Revenue, and any extra revenue generated unlikely to cover the cost of collecting it.
When I last worked in UK, my airline (major UK Charter Operator) had a deal with the Inland revenue whereby we paid 25% tax on 25% of our allowances, deducted at source. Eg, Monthly allowances 1600, tax burden 100. It worked well and was simple to administrate.
More power to the beancounters I guess!
edited for appalling grammar.