Cat A vs Cat B fit-out: the difference explained

The short answer

A Category A fit-out is the landlord's work: raised floor, suspended ceiling, basic lighting and distributed services, delivered so the floorplate can be marketed and let. A Category B fit-out is the tenant's work on top of it: the layout, meeting rooms, joinery, finishes, branding and furniture that make the space usable by one specific business.

Everything else in this guide follows from that split. Cat A is a property cost, recovered through rent. Cat B is an occupier project, budgeted, designed and procured by the business moving in.

What each stage actually delivers

The table below tracks the same building elements through the four stages a UK office typically passes through. Where an element appears twice, it is because the later stage alters or replaces what the earlier one installed, which is exactly where money gets wasted on badly sequenced projects.

Shell and core: where a building starts

Shell and core is the developer's handover. The structure, external envelope, roof, lift cores, stairs, toilets and main plant are complete, and the risers carry services up the building. The floorplates themselves are bare concrete with capped connections waiting at the riser door.

You will meet shell and core on new build and on major refurbishment, where a landlord has stripped a tired building back to its frame. It is occasionally let directly to a large occupier who wants full control of the fit-out, in which case the tenant takes on the Cat A works as well as the Cat B, usually against a longer lease and a stronger incentive package.

Category A: making the floor lettable

Category A takes a bare floorplate to a finished, empty, marketable state. It is a defined package rather than a design exercise, and one Cat A floor looks much like another. Typically it includes:

• Raised access floor, laid but with no floor covering.
• Suspended ceiling grid and tiles.
• Basic lighting, set out on the ceiling grid rather than to a layout.
• Heating, cooling and ventilation distributed across the floor and capped off.
• Fire detection, alarms, sprinklers and emergency lighting to base-build standard.
• Painted perimeter walls and columns, and finished common areas and toilets.

What it does not include is any of the things that make an office an office. There are no meeting rooms, no tea point, no reception, no data cabling, no furniture and no floor finish. Standing on a completed Cat A floor is the moment most occupiers realise how much of the budget is still ahead of them.

Category A+: the landlord does the Cat B

Cat A+, also sold as plug and play, fitted or ready-to-occupy space, is a landlord-funded fit-out delivered before the letting. The landlord installs meeting rooms, a tea point, cabling, furniture and a neutral scheme, then lets the space furnished, often on a shorter and more flexible lease.

For a small or fast-growing occupier the appeal is obvious: no capital project, no design team, no six-month programme, and a move-in measured in weeks. The trade-off is that you take someone else's layout and pay for it through rent over the term rather than once at the start. For a business with settled requirements and a long lease, a bespoke Cat B usually works out better on both cost and fit.

Category B: the occupier's fit-out

Category B is where the design work lives. It covers the space plan, partitioning and glazing, alterations to the Cat A ceiling and lighting, rebalancing of the ventilation to the new layout, small power and data, joinery, decoration, floor finishes, kitchens, and the audio-visual and furniture packages.

It is also the part with real cost variance. A largely open-plan scheme reusing the Cat A ceiling sits at the bottom of the market range; a cellular, heavily serviced headquarters with bespoke joinery sits several times higher. Our office fit-out cost guide sets out the published per-square-foot bands and what drives movement between them.

Who pays for what

The default position across the UK market is straightforward: the landlord funds shell and core and Cat A, because that is the cost of having lettable space. The tenant funds Cat B, because that is the cost of occupying it.

Landlord contributions to Cat B are common, but they rarely appear as a build budget. They are negotiated into the lease as a rent-free period, a stepped rent, or a capital contribution paid against certified works. Two consequences follow. First, the incentive is worth comparing against the fit-out cost, not against the headline rent. Second, a capital contribution usually comes with conditions on who does the work and what evidence of spend the landlord will accept.

Reinstatement: the cost at the other end

A Cat B fit-out is normally a liability as well as an asset. Most leases require the tenant to reinstate the premises to Cat A condition at expiry, which means stripping out the partitions, joinery and finishes that were just installed and making good behind them.

Three things reduce the eventual bill. Agree a photographic schedule of condition before any work starts, so the reinstatement standard is evidenced rather than argued. Get the licence to alter to describe precisely what may remain at the end of the term. And keep the strip-out cost in the project appraisal from the beginning, alongside the dilapidations on the space you are leaving.

Who builds which stage

The stages are usually procured from different kinds of firm, which is worth knowing before you send an enquiry to the wrong one.

• Shell and core and Cat A go to main contractors and commercial builders, who take principal contractor duties for the whole building. The register lists these under commercial building construction.
• Cat B goes to fit-out contractors and office refurbishment specialists. See the commercial fit-out index and the office refurbishment index.
• Retail, bar and restaurant schemes follow the same Cat A and Cat B logic but are usually delivered by shopfitters and shopfitting companies, whose workshops make the fixtures as well as install them.

Whichever route you take, check the firm before you invite it to tender. Every entry on this register carries the company number, incorporation year and registered address, drawn from the Companies House record. You can filter by area from the region index, or search the whole contractor register directly.

Common questions

What does a Cat A fit-out include?

A Category A fit-out delivers a lettable but unfinished floor: raised access floor, suspended ceiling, basic grid lighting, distributed heating, cooling and ventilation, fire detection and sprinklers, and painted walls. There are no meeting rooms, no joinery and no furniture.

What is a Cat A+ fit-out?

Cat A+, sometimes called plug and play or fitted space, is a landlord-funded Category B fit-out delivered before letting. The tenant moves into a furnished, cabled office on a shorter lease, paying through the rent rather than a capital project.

Who pays for Cat A and Cat B works?

The landlord funds Cat A as the cost of making space lettable. The tenant funds Cat B. Where a landlord contributes to Cat B, it normally comes as a rent-free period or a capital contribution negotiated in the lease rather than a separate build budget.

Do I have to strip out a Cat B fit-out at the end of the lease?

Usually yes. Most leases require reinstatement to Category A condition, so the partitions, joinery and finishes you install become a dilapidations liability later. Agree the reinstatement position and the photographic schedule of condition before works start.

Can Cat A and Cat B be built at the same time?

Where a tenant signs early enough, yes, and it saves money. Running the two together avoids installing a Cat A ceiling grid and lighting that the Cat B works immediately alter, but it needs the landlord, both design teams and one contractor aligned from the start.