One record, one place: what single source of truth actually means in practice
“But Excel is free” is one of the more expensive sentences you’ll hear in an operations meeting. The licence is free. The time isn’t.
What follows is a worked example, drawn from a real engagement (anonymised, with a few details adjusted). The numbers are conservative. Most readers will recognise their own organisation in some of it.
The setup
A diocesan housing portfolio: 84 properties, 110 tenancies, six staff in the housing office. Pre-engagement, everything ran on a master Excel workbook called HOUSING_MASTER_v47_NEW_DO_NOT_DELETE.xlsx. There were also 11 supporting workbooks, three Word document templates, and a OneDrive folder of 3,200 PDFs.
The team was excellent. The system was the problem.
Where the time was going
1. Re-keying the same fact in three places
A new tenancy meant: typing the tenant’s details into the master workbook, into a separate "rent ledger" workbook, and into the inspection-schedule workbook. Twenty minutes per tenancy. Fifteen new tenancies a year. Five hours.
2. Reconciling versions
By Friday lunchtime there were typically four versions of the master workbook in circulation: Susan’s on her laptop, Mark’s emailed copy, the "official" one on SharePoint, and the one the bursar had downloaded on Tuesday and was still working in. Reconciling on Monday morning took about an hour, weekly. Fifty hours a year.
3. The compliance-check ritual
Every quarter, someone went through 84 properties to check which gas certificates, electrical certificates, EPCs, fire risk assessments and asbestos surveys were due in the next 90 days. With Excel filtering and conditional formatting, this took about a day and a half. Six days a year, just on visibility.
4. The audit
Annual diocesan audit. The auditor wanted: gas-cert dates per property, repair-spend per property over the last three years, void-period analysis, and a compliance summary. Each of these required Excel surgery on workbooks that didn’t quite agree with each other. The audit prep was a fortnight of full-time work for one person. Ten days.
5. "Where’s that document?"
Tenant queries about lease terms, repair history, last inspection. Average 20 a week. Each one a five-minute hunt through the OneDrive folder. One hundred and ten hours a year.
6. The handover problem
The year before our engagement, the housing officer who’d run the spreadsheet for eight years went on maternity leave. The handover took three weeks of overlap, mostly spent explaining which workbook was the real one, which formulas were precious, and which cell had the magic VLOOKUP everyone was afraid to touch. Three weeks of two people, every time someone leaves.
7. The mistakes
Two we know about. A gas certificate that lapsed for eleven days because it was filtered out of a stale view. An accidental rent-statement export with the wrong column headers, sent to 30 tenants. Each cost the team a day of remediation; the second cost the diocese its annual ICO breach allowance. Unquantifiable, but not zero.
Adding it up
| Activity | Hours / year |
|---|---|
| Re-keying new tenancies | 5 |
| Weekly reconciliation | 50 |
| Quarterly compliance check | 48 |
| Annual audit prep | 80 |
| Tenant document hunts | 110 |
| Handover overhead (amortised) | 40 |
| Total | 333 hrs |
Three hundred and thirty-three hours a year is roughly half a full-time-equivalent. At a fully-loaded staff cost of £35k, that’s about £17,000 a year going on the spreadsheet’s administrative overhead alone. Excludes the unquantified cost of the mistakes.
What replacing it bought back
After migration to a proper database-backed system: the re-keying, the reconciliation, the compliance ritual and the document hunts collapsed to roughly thirty hours a year combined. Audit prep dropped to a day. The handover problem went away because the system is the institutional memory; nobody needs to know which cell has the magic formula because there is no magic formula.
Net time saved: about 275 hours a year. The system pays back its build cost in roughly 18 months and then it’s pure surplus, year after year.
The wider point
Excel is free in roughly the same sense that running an organisation out of a single shared inbox is free. The licence costs nothing; the chaos that grows up around it costs a lot. The people doing the chaos are usually too busy doing it to count.
If your team has a spreadsheet they couldn’t live without, it’s worth taking a quiet hour to add up where the time goes. It probably costs more than you think, and the maintenance is always one person away from a crisis.
If you’d like a second pair of eyes on yours, drop us a line.