Lost/Abandoned cat wants to enter house; advice needed

This is a very common problem we see in this Stack Exchange.

• You had a great plan. Getting a carrier and seeing a vet for microchips is the best approach.
• In case it is not microchipped, prepare a paper collar. You basically write your details on a paper and wrap it around his neck. Make sure that the paper is not too thick, otherwise the animal might be strangled.
• If you decide to keep feeding him for some time, you might want to have an easy break collar with your details on a nametag. Collar and nametag would cost you £5 only.

Hopefully an owner will come forward and this will be the end of your troubles.

You have every right not to admit the cat into your house. Although it is small, there is always the risk of ticks, so I would also recommend you to use caution. Housecats find it hard to readjust to outside accommodation. If you decide to hang onto the cat but still prefer to keep him outside, have a sturdier shelter than a cardboard box. Still, cats can be stupid so he might not be using the shelter so feed him only in the near vicinity of the shelter. Adult cats, as long as they are well fed, not wet and have a good shelter with have a blanket to warm themselves can easily survive cold nights of 0 degrees centigrade. Make sure that the shelter has a very small opening and a cosy corner to help your cat evade the wind. Such a shelter would also gave him an edge against stray cats.

It would help him a lot if you have a garage where he will be separated enough from your household but protected against other stray cats and wind.

Also, if you decide to hang onto the cat but want to keep him outside, you need to put him for adoption as well. The shelter and the interaction that I described is enough to sustain the cat but not enough to keep him happy.

Why does he want to get in?

Cats are unable to grasp private property and they are the only domestic animal that have a right to trespass at will. Therefore, they spend their life looking for shelters that would keep them happy and healthy. This includes interactions with humans as well as food and shelter. Even if he has an owner who feeds him regularly, he will still want to come in because they like to hedge their investments in humans.

If you don't want him to scratch your door, make sure not to give in to his scratches. Ignoring is the best option. If he knows he can get in by repetitive scratching, he would do it. You can also spray his face with water as long as the weather is not cold when he scratches. But you have to do it as the cat scratches the door otherwise he won't make the connection.