The verdict in three sentences
An independent agency with 350 temps on assignment every week handles more than 1,400 timesheets a month, and every paper or PDF timesheet keyed in by hand is a source of payroll errors and late invoicing. Off-the-shelf software at GBP 350 to 1,300 a month (EUR 400 to 1,500) covers assignments, right-to-work checks and standard payroll, while a custom build at GBP 43,000 to 105,000 (EUR 50,000 to 120,000) makes sense when industrial clients impose their own overtime and shift premium rules. Done well, the project cuts invoicing from 10 to 3 days and payroll errors by a factor of 4.
The real cost of paper and spreadsheets
Across London and the M25 belt, warehouse, food production and facilities assignments mean night shifts, split shifts and site-specific premiums. Every manual timesheet goes through 3 people: the client who signs it, the consultant who collects it and the payroll officer who re-enters it.
| Indicator | Paper or PDF timesheets | Digital timesheets (2026 estimate) |
|---|---|---|
| Timesheets per month | 1,400 to 1,500 | Unchanged |
| Processing time per timesheet | 6 to 8 min | 1 to 2 min (online client approval) |
| Payroll error rate | 4% of payslips | 1% of payslips |
| Client invoicing delay | 10 days after week end | 3 days |
| Pay advance requests from temps | 30 to 50 per week | Self-service |
| Assignment terms signed same day | 70% | 98% (e-signature) |
On monthly revenue of GBP 1,050,000, invoicing 7 days earlier frees about GBP 245,000 of cash, a major lever when the agency funds payroll every week.
Off-the-shelf or custom: the comparison
| Criterion | Staffing software | Custom build |
|---|---|---|
| Entry cost | GBP 2,600 to 10,500 (setup, migration) | GBP 43,000 to 105,000 |
| Monthly cost | GBP 350 to 1,300 | GBP 600 to 1,300 (maintenance, hosting) |
| Time to go live | 1 to 3 months | 5 to 8 months |
| PAYE, RTI, holiday pay, pensions auto-enrolment | Included and maintained by vendor | Must be built or connected to a payroll engine |
| Client-specific premium rules | Limited configuration | Custom rules engine |
| Temp app (shifts, timesheets, advances) | Standard | Branded, mobile-first |
| Client portal (hours approval, invoices) | Basic | Built into your process |
Temp payroll is heavily regulated in the UK: RTI submissions, holiday pay accrual at 12.07% for irregular hours, pensions auto-enrolment, Agency Workers Regulations parity after 12 weeks. The safest route is often hybrid: keep a proven payroll engine and build the temp app, client portal and premium rules engine around it.
The scope that delivers the ROI
| Module | Expected gain | Indicative budget |
|---|---|---|
| Digital timesheets approved by the client | 5 to 6 min saved per timesheet | GBP 8,500 to 17,500 |
| Automated assignment terms and e-signature | Signed before the first shift | GBP 7,000 to 13,000 |
| Premium rules engine per client | Payroll errors cut by 4 | GBP 10,500 to 26,000 |
| Temp mobile app | 60% fewer calls | GBP 10,500 to 22,000 |
| Automatic invoicing and accounting export | Invoice on day 3 | GBP 7,000 to 15,500 |
Mini case study
James runs an independent staffing agency in East London, 350 temps a week, 1,450 timesheets a month. Two payroll officers spend 7 minutes per timesheet, about 170 hours a month. Payroll errors hit 4% of 1,500 monthly payslips, each costing GBP 40 on average to correct, or GBP 2,400 a month. He commissions a client-approved timesheet app, a premium rules engine and automatic invoicing for GBP 59,000, connected to his existing payroll software, plus GBP 870 a month of maintenance. Gains: 135 hours a month at GBP 26 loaded (GBP 3,510) and GBP 1,800 fewer errors, about GBP 5,300 a month, plus 7 days of cash recovered. Payback in under 14 months, before counting short-term financing costs avoided.
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FAQ
Can custom software run RTI and temp payroll?
It can, but it is costly: GBP 35,000 and up for a compliant payroll engine, with permanent regulatory monitoring. Most agencies under 1,000 temps keep a vendor payroll engine.
Will clients approve hours online?
In practice, 80 to 90% of clients switch within 2 to 3 months if approval takes under a minute on mobile. Keep a PDF option for the rest.
How are pay advances handled?
The app lets temps request a capped advance, for example 50% of approved hours, which removes 30 to 50 calls a week.
How long is the rollout?
Budget 5 to 8 months for a custom build, including a 4-week pilot with 2 or 3 clients before going wide.
Are electronically signed assignment terms valid?
Yes, a simple e-signature is valid under UK law for terms of engagement, provided the key information document is issued before the temp starts work.
Let's scope your project. Send us your weekly temp volume, your payroll software and your main premium rules: we will price a hybrid or full solution with a week-by-week plan and the cash flow it frees. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
