Move off a spreadsheet when more than one person depends on it, when a wrong number in it costs real money, or when nobody but its author can safely change it. Below that bar, fix the spreadsheet. Above it, a proper system starts around £7,000 to build and £100 a month to run — well under the £10,000–£30,000 UK agencies quote for even a simple internal tool.
We build these, and we also sell an off-the-shelf product, so we have no reason to talk anyone into the expensive answer. We regularly tell firms their spreadsheet is fine.
The four things that actually break
Spreadsheets do not fail dramatically. They degrade, and every symptom below is a version of the same root cause: a spreadsheet has no idea who did what, or when, or whether it was allowed.
1. Nobody knows which file is real. The moment a second person needs the data, you get Leases_v3.xlsx, Leases_v3_FINAL.xlsx and Leases_v3_FINAL_use_this.xlsx. Two departments quote different numbers in the same meeting because both are technically reading "the" spreadsheet.
2. One person is the system. There is always somebody who built the macros and understands why column AF must never be sorted. That is not a spreadsheet risk, it is a staffing risk. When they are on holiday the business slows down; when they leave, it stops.
3. Everyone can see and change everything. A spreadsheet has no concept of a role. The person who needs to update one field can also delete the other four thousand, see the salary tab, and email the lot to a personal address. There is no record that any of it happened.
4. The errors are already in there. This is the part firms underestimate. A 2024 study of business spreadsheets used in decision-making found critical errors in 94% of them, and earlier research puts material defects in around half of the models used by mid-sized and large businesses. Experienced users still get 2–5% of formula cells wrong. Those are not other people's spreadsheets.
When you should NOT replace it
We put this first because it is the answer more often than the industry admits. Keep the spreadsheet when:
- One person owns it and that is genuinely fine. A spreadsheet is an excellent single-player tool. It only becomes a liability when it goes multiplayer.
- The process is still changing every week. A system makes your process permanent. If you do not yet know what the process is, a spreadsheet is the cheapest way to find out — keep using it until it settles.
- It is annoying rather than expensive. Annoying is not a business case. Price the annoyance in hours before you price a build.
- A ready-made product already fits. If something off-the-shelf does your job properly, buy it. It costs like software, not like a build.
Three of those four cost you nothing to act on. That is deliberate.
The moment it is genuinely time
The clearest signal is not frustration, it is consequence. Move when a mistake in the spreadsheet costs money rather than time: a date missed, a renewal not chased, an invoice not raised, a figure reported wrong to a board or a lender. At that point the spreadsheet is not an admin tool, it is a control — and it has none of the properties a control needs.
The second signal is arithmetic. If someone loses two hours a day to retyping between systems and rebuilding the same report, that is roughly ten working weeks a year. Put your own hourly figure against ten weeks and compare it to £7,000.
What "a system" actually means
The word does a lot of hiding, so here is the concrete version. A system is four things a spreadsheet cannot do:
- One set of records. Not a file that gets copied — a single place everything else reads from, so there is no "which version".
- Rules that hold. The fields that must be filled are filled, the dates that must be valid are valid, and the system refuses the entry rather than quietly accepting a typo.
- Roles. Ten people can look, two can edit, and every change has a name and a timestamp against it.
- Things that happen without anyone remembering. The reminder before the date, the report on the first of the month, the record created when the form is submitted. This is usually the part that pays for the build.
Notice that none of those are features. They are properties. That is why "we added a tab for it" never quite works.
What it costs in the UK
UK agencies that publish figures for this work quote £10,000–£30,000 for a simple internal tool and £30,000–£80,000 for a mid-complexity system with integrations — and almost always as a range rather than a price. Timelines quoted are commonly four to eight weeks for something simple and three to five months for something larger.
Ours is £7,000 to build and £100 a month to run, scoped and agreed in writing before anything is paid. That covers the records, the rules, the roles, the reminders, your branding and your own domain, with your spreadsheets loaded for you and as many users as you need. The full breakdown is on the Proprietary Database page.
If your shape is a property portfolio specifically, do not commission a build at all — TenureBook already is that system, from £295 a month, live the day you sign up. A ready-made product built for your exact sector beats both a generic tool and a bespoke build whenever one exists.
What happens to the data already in the spreadsheet
Nothing is retyped. That is worth stating plainly because it is the fear that stalls most of these decisions.
Your spreadsheet is the specification: the columns tell us what you track, and the mess in them tells us where the process actually breaks. We map the columns to fields, load the history, and show you what came across before anything goes live. In TenureBook the same job is a few clicks — it reads your columns, shows you what it found, and builds the records from there.
One we did
Our first client was a UK commercial-property firm running a whole portfolio out of spreadsheets. The thing they were tracking was not really a row — it was a lease, with dates attached that cost real money when missed, documents that belonged with it, and figures that had to reconcile.
We built them a Proprietary Database: companies, properties, leases, financials, documents and reminders in one place, with the reporting on top. They have run on it every day since the start of July. You can see what it looks like on the case study.
That build is also why we can say the off-the-shelf answer is often right without it being false modesty: the lessons from it became TenureBook, so we now sell the product that makes that particular build unnecessary.
How to decide this week
- Open the spreadsheet and count how many people need it. If the answer is one, stop here.
- Write down the last three things that went wrong because of it, and what each cost — in money, not in irritation.
- Ask what happens if the person who maintains it leaves tomorrow.
- If steps two and three produce real numbers, compare them to £7,000. If it is not close, keep the spreadsheet and tidy it.
If you want a second opinion from someone who will tell you to stay put when that is the right answer, book a short call, or send us what your firm tracks and we will come back with exactly what a system for it would include and cost.