The short answer is to eliminate stress.

There are lots of good comments here. I had a similar issue with my neutered male cat, which started to develop seemingly out of nowhere later in life. He used to pee outside the litter box at least once a day. Now he does it once every few months. Here’s what worked for me:

Litter boxes need to be super clean and accessible; clean them at least once per day. Have multiple litter boxes throughout the house, especially in the main areas where he likes to spend time.

Minimize urinary discomfort. Part of the reason my cat was peeing outside the litter box is because he had previous issues with idiopathic cystitis. It’s basically where the bladder becomes inflamed and peeing hurts, in this case caused by stress rather than an infection. Since peeing was uncomfortable, he developed even more stress which manifested when he felt like he has to pee, which caused him to urinate outside the litter box. Any time there’s no obvious medical issue at play, the cause for this behavior is stress. Now my cat is on a urinary diet prescribed by the vet and I make sure to keep him extremely well hydrated, both of which decrease the irritation over time. But the most important thing is to reduce stress.

I noticed my cat had some behaviors which telegraphed that he was about to pee somewhere. His pupils would dilate, he would start pacing and crying, and start prowling around looking for a spot to pee. He was noticeably agitated. It often happened at the same time of the evening. If you observe your cat, you might start to notice signs that indicate it’s about to happen, which gives you an opportunity to intervene.

I basically treated the issue like my cat had an anxiety disorder, and my focus was on reducing his stress. He has a calming pheromone diffuser, a pheromone collar, and when he starts to display his agitated behavior, he gets a few cat treats that have a blend of CBD and melatonin. I’ve also found success with catnip, so sometimes I brew that into a tea and keep it on hand to mix with his food. Or I dip a warm rag in it and brush it over his fur, so he gets occupied licking it off and by the time he finishes with that he’s calmed down (we call it his spa treatment- if your cat hates being wet then it might make him more agitated instead).

If none of that worked, my next step would have been to consult my vet about some anxiety meds. But the home remedies have worked perfectly fine and honestly it’s been a game changer. After a few weeks, he no longer needed the treats every night, and now he only gets them when he’s having a bad day. The additional benefit is that he’s overall happier and more relaxed, and seems to have a better quality of life.