No , mathepac . Its the MPRNs and GPRNs that match up but ROS insist on invoice numbers as well and they might look for invoice copies later in some cases so better get it right first time. Anyway I'm actually finding in some cases ( and maybe somebody better at maths than me might check it that ROS are actually multiplying the difference in bill costs by 40% TWICE , which accounts for businesses receiving a 16% rebate instead of a 40% rebate in error. I checked my figures against the Revenue online calculator and using my own treple check spreadsheet calculations. Adminstrators , if I am incorrect with this please delete this post so I don't confuse anybody.