We had building work done in 2010 (when VAT was 17.5%). We paid the bill inc 17.5 VAT. But the final bill did not include some extras we'd had done as the builder was waiting for the subcontractor accounts to be returned. Now after A YEAR he has finally billed us a hefty amount for all the extras at the new VAT rate of 20%.
I think that we should pay 17.5% as it was work done and completed in 2010 even though the invoice did not arrive until Dec 2011 but I can't find any info on this. Does anybody know????