A Jaffa Cake is a cake.
This question was actually answered in court by the UK's tax revenue department, HMRC.
According to British law, when a biscuit is covered in chocolate, it becomes subject to 17.5% VAT tax.
To avoid this levy, the company who makes Jaffa Cakes (McVities UK) were forced to defend their claim that Jaffa Cakes are a cake in court.
How did they prove it?
They applied a very scientific test.
As we all know, when cakes are left out for a long time - they begin to go hard.
If you leave a biscuit out of the biscuit tin over night, it begins to turn soft.
When applying this to a Jaffa Cake, it behaves as a cake would be expected to and turns hard.
This was the deciding factor in the court case, which is why the price of a Jaffa cake is 17.5% less than if it were a biscuit.
