HMRC names reference material as an example of something that would not be a leaflet, and a recipe card is the clearest case of it: the point of the card is that it goes in a box, on a fridge or in a drawer and is used again. The same reasoning covers swatch and shade cards, index cards, flash cards and pattern cards, all of which the notice lists as standard-rated. The difference between this and a recipe book is worth knowing, because it is not about quality: recipe books are listed as zero-rated, because bound pages of reading matter are a book however often you cook from them.
What decides it?
A card kept for reference is standard-rated. The same recipes bound into a book are zero-rated.
Where does this come from?
HMRC VAT Notice 701/10, paragraph 3.3, HMRC's guidance on zero rating books and printed matter. See the notices we work from.
Some real jobs
A boxed set of 40 recipe cards on 350gsm board20%
Reference material, kept and used. HMRC names reference material as outside the leaflet meaning.
The same 40 recipes as a stapled A5 booklet0%
Recipe books are listed as zero-rated.
A single recipe leaflet given away with a bag of flour0%
A leaflet may be designed to accompany another product.