Judge the cupboard by your cat's route in, not by how tidy it looks
A hallway cupboard appeals to owners because the tray disappears behind a door, but your cat judges the space entirely differently: can she reach it at three in the morning, enter without pushing against anything that swings or sticks, turn around comfortably inside, and leave quickly if a noise startles her mid-visit? Measure the interior with the tray in place and allow standing and turning room beyond the tray itself, because a cupboard that only just fits the box forces her to step in her own litter and track it down the hall. If the cupboard houses a boiler, cleaning chemicals, or a vacuum she fears, it is the wrong cupboard no matter how convenient the location seems.
Guaranteeing access around the clock
The door is the whole project. A cat flap cut into the cupboard door is the most reliable option because it works whether the door is shut for visitors or left ajar on an ordinary day, and a flap sized generously for your cat, including any weight she may gain, avoids the squeeze that puts cats off enclosed trays. If cutting the door is not possible in a rented home, fix the door permanently ajar with a door strap or latch that holds a cat-width gap and cannot swing shut, and brief everyone in the house that this door is never closed.
Ventilation that clears smell without creating a draught she hates
Enclosed spaces concentrate litter smell fast, and a cat's nose is far more sensitive than yours, so stale air inside the cupboard is the most common reason cats abandon an otherwise good setup. Louvred door panels or a vent grille fitted low on the door let air exchange passively with the hallway, while a small vent high in the cupboard wall, where the structure allows it, lets warm stale air escape. Avoid plugging in anything noisy inside the space; a humming fan inches from the tray will deter a nervous cat far more effectively than odour ever would. Daily scooping remains the real ventilation, because no vent compensates for waste sitting in a small sealed box, so judge your setup after a full day: if you can smell it with the door open, she could smell it long before you could.
Flooring, lighting, and cleaning reach inside the cupboard
Line the whole cupboard floor with one washable mat that extends well beyond the tray, since cats step out and shake litter from their paws within the first stride, and a mat you can lift out and shake beats scrubbing a cupboard floor on your knees. Choose an open tray rather than a hooded one inside an already enclosed cupboard; doubling the enclosure traps smell at nose level and many cats refuse the combination. Add a low, warm motion light or leave a dim hallway light nearby, because cats see well in low light but a pitch-black cupboard interior behind a flap is a harder sell, especially for an older cat.
Helping the household respect the station
Cupboards collect clutter and visiting hands close doors, so a litter cupboard needs household rules more than most setups. Keep nothing else stored in there once it is a litter station, label the door strap's purpose for guests, and make the cleaning rota explicit so the hidden tray is never the forgotten tray. Family members chosen by the owner may be given access to that profile under KinsLe Family Sharing.