The update
it's still the same really,If you buy a 'breeding cat' even if your intention is to 'hobby breed' you are a business & will need to complete tax returns showing any profit and of course any expenses incurred.
I think if you are a small breeder then the HMRC will accept that the occurence or a profit may be minimal or unlikely especially if you have a run of bad luck with vet bills!
The HMRC are unlikey to proceed with investigations against you if you only deal in cash, don't mention prices on any adverts, don't have all your breeding cats on your website and don't actually mention how many kittens you have had in each litter.
But I do worry that if some breeders are going to go to such great lengths of dishonesty to save paying the tax man a few extra pounds (let's face it the HMRC are about as official as they come) how honest will they really be to either the buyer of their pet or breeding kittens?
You never really know who is making the initial enquiry into buying a kitten, it could be Joe Bloggs equally it could be an agent working for the HMRC trying to 'catch' you out.
So you may have guessed that I will be completing tax returns for the past & future but I'm shocked at how much expenditure I've had over the last few years! It's very frightening when you actually see it written down!
I wouldn't let this put you off breeding if it truly is something you have a passion for - as they say 'nothing is certain but death & taxes'