Payroll has no slack in it. The Full Payment Submission has to reach HMRC on or before payday, every NI and tax figure has to be right, and a wrong payslip is something an employee notices immediately. For a lot of UK businesses, that pressure is still being managed with spreadsheets, manual checks, and a payroll product that doesn’t quite fit how they pay people.
Off-the-shelf payroll software solves part of this and creates new problems elsewhere. You bend your process to fit the tool, you pay a per-employee fee that climbs every time you hire, and the awkward parts of your payroll, the commission rules, the shift premiums, the second site, still get handled by hand.
We build custom payroll automation software designed around your pay structure and your compliance obligations. It’s developed in the UK, it carries no per-employee subscription, and you own the code outright. We’re a small London consultancy, and we’re honest about when a bespoke build is worth it and when a recognised SaaS product will serve you better.
Where off-the-shelf payroll software falls short
A recognised SaaS payroll product is genuinely the right answer for a lot of businesses. It tends to fall short in specific, predictable ways once your payroll stops being simple:
- Per-employee pricing scales against you. Most platforms charge a base fee plus a monthly amount per employee. It looks cheap at 15 staff and stops looking cheap at 150. Add benefits, time tracking, advanced reporting and premium support and the real bill is well above the headline.
- Rigid commission and deduction logic. Variable pay tends to be locked into a few fixed tiers. Multi-tier commission, clawback, retention bonuses, piecework, union dues and one-off adjustments either don’t fit or need a vendor support ticket.
- Approval workflows you can’t shape. Many products can’t route sign-off by cost centre or business unit, and can’t flag an unusually large payment for an extra check. The audit trail is often thinner than a regulated business needs.
- Integrations that stop at the big names. Xero and QuickBooks are usually fine. A legacy GL, a proprietary HR database or an in-house time-tracking tool often isn’t, and stitching it together with webhook tools is not something you want carrying compliance-critical payroll data.
- Global platforms that are thin on UK detail. Some larger international products treat RTI, auto-enrolment edge cases and CIS as afterthoughts, and UK-hours support can be slow when you most need it, around month-end and tax year-end.
- Multi-entity pain. Grow by acquisition and you can end up running payroll across two or three systems with no consolidated view.
The real cost here isn’t the licence fee. It’s the manual workarounds, the corrections, and the compliance risk that sits on top.
When SaaS is enough, and when a custom build pays off
We’d rather you spent your money well, so we’ll say this plainly.
A recognised SaaS product is usually the right call if your payroll is straightforward, salary plus overtime and standard deductions, on a single UK entity, with normal RTI and auto-enrolment needs and no integration beyond Xero or QuickBooks. Below roughly 100 employees, the subscription is rarely the thing holding you back.
A custom build starts to make sense when one or more of these is true:
- Complex or variable pay: multi-tier commission, clawback, piecework, shift differentials, project-based cost allocation
- Several entities or sites that need consolidating into one source of truth
- Approval or audit requirements that off-the-shelf workflows can’t express
- Integration with legacy or proprietary systems that no SaaS connector covers
- A headcount large enough that per-employee pricing has become a meaningful annual cost
- An industry with payroll rules generic platforms simply don’t handle well
- A genuine need for full data ownership, or to white-label payroll as a service to your own clients
What we build instead
We map your actual payroll process first, then build software around it. A typical build includes:
- A payroll engine that fits your pay rules. Salaried, hourly and pro-rata calculation, overtime, bonuses, allowances such as London weighting and on-call, and the deduction logic your business actually uses.
- PAYE, NIC and RTI handled properly. Tax code application, National Insurance, and valid Full Payment Submission and Employer Payment Summary files generated for HMRC to the correct schedule.
- Pension auto-enrolment. Eligibility assessment, contributions on qualifying earnings, opt-in and opt-out handling, three-yearly re-enrolment, and the statutory communications, working with NEST, The People’s Pension, Aviva and others.
- Statutory payments. SSP, SMP, SPP and Shared Parental Pay calculated, tracked, and reflected in RTI.
- CIS where you need it. Subcontractor verification, deduction at source, and monthly CIS returns for construction businesses.
- BACS payment files and clean accounting posting. Generate the bank payment file, and post wages, tax and pension costs to Xero, QuickBooks or Sage without rekeying.
- An employee self-service portal. Payslips, P60s and P45s, plus the ability for staff to update their own details, on desktop and mobile.
- Reporting built for your business. Payroll cost by department or cost centre, headcount and FTE, year-on-year trends, and exports your accountants and management actually use.
- Role-based access and a full audit trail. Finance, HR and approvers see what they should, and every change is logged with who, when and what.
The core entities, employees, salary records, deductions, pay records, payroll runs, approvals and statutory records, are modelled around how your business is structured, not a generic template.
How the build works
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Discovery and planning (2 to 3 weeks)
- We work through your current payroll process, pay rules and compliance obligations in detail
- We map your data: employee records, year-to-date figures, deductions, approval hierarchies
- We agree the MVP scope and what’s deliberately deferred to phase two
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Development (6 to 16 weeks)
- Agile, with regular working builds so you can see progress
- Core payroll, PAYE and NIC, payslips, BACS files and RTI submission built first
- A UK-hosted staging environment so finance can try it early
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Testing and parallel running
- End-to-end testing of calculations and every integration together, not in isolation
- At least one or two parallel pay cycles, new system alongside the old one, before anything goes live
- Careful data migration, with year-to-date figures reconciled against P60s
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Go-live and support (ongoing)
- We deliberately avoid cutting over close to month-end or tax year-end
- The old system stays available as a fallback until the new one is proven
- Training for finance, HR and approvers, plus documentation
- Tax-year and regulatory updates handled under a support package
An MVP covering core processing is often live in 6 to 16 weeks; auto-enrolment, time-tracking sync, advanced approval workflows and custom reporting usually follow in a second phase. Skipping the parallel run or migrating during a year-end crunch are the two most common ways payroll projects go wrong, so we don’t do either.
What it costs and what you own
A custom build is a larger one-off cost than a monthly subscription. Whether it pays back depends on your situation, and we’ll be straight about that.
- SaaS is rented; a custom build is owned. SaaS cost compounds with every hire and every add-on module. A custom system is a fixed build cost plus modest ongoing maintenance.
- The crossover is usually headcount-driven. For larger payrolls and multi-entity groups, several years of per-employee subscriptions plus integration and support fees can match or exceed a bespoke build. Below around 100 employees, that’s often not the case.
- No vendor lock-in. You own the code and the data. You can export anything, change hosting, and add features later without an upgrade charge or a contract renewal hanging over you.
- Fewer corrections and less compliance exposure. A system built around your real rules produces fewer payslip errors, late filings and underpayments to chase.
We won’t promise a guaranteed payback date or quote you against a rival’s exact price, both move too much to be honest about. In a free consultation we’ll model your three and five-year total cost both ways and tell you which makes sense.
Where this gets used
Payroll is rarely the same twice across industries. The hard parts tend to be sector-specific:
- Healthcare: night and weekend shift differentials, agency and locum rates, credential and CPD expiry tracking, payroll reconciled against rostering
- Hospitality and catering: tip pooling and fair distribution, weighted overtime thresholds, multiple job rates within a single shift, zero-hours and casual workers, POS integration
- Manufacturing and engineering: piecework pay, shift allowances, production-linked bonus tiers, cost allocation to projects and cost centres
- Construction: CIS subcontractor verification, deduction at source, monthly returns, mixed PAYE and CIS workforces
- Professional services: project-based cost allocation, billable-versus-payroll reconciliation, partner and shareholder distributions, utilisation-linked bonuses
- Non-profit and charity: salary costs split across restricted funding streams, program-level cost allocation, funder reporting, pay-ratio compliance
- Multi-site groups and franchises: payroll across several entities consolidated into one reporting view
Whatever sector you’re in, we build the system around the parts of payroll that are genuinely awkward for you, and leave the rest simple.
Common Questions About Custom Payroll Automation Software
How does custom development cost compare to SaaS payroll software?
SaaS payroll usually charges a base fee plus a per-employee monthly amount, so the bill grows every time you hire. A custom build is a larger one-off cost with low ongoing maintenance. For smaller headcounts SaaS is often the cheaper and more sensible option. The maths tends to shift once you pass roughly 100-150 employees, run payroll across several entities, or pay extra for integrations, premium support and add-on modules. We'll model your three and five-year cost honestly before you commit.
What's the typical development timeline?
A working MVP covering core processing, PAYE and NIC calculation, payslips, BACS files and RTI submission usually takes 6 to 16 weeks depending on headcount and complexity. Pension auto-enrolment, approval workflows, time-tracking sync and custom reporting are normally added in a second phase. We deliberately avoid going live close to month-end or tax year-end.
How do you handle HMRC and tax year changes?
Tax thresholds, NI rates, statutory payment limits and pension figures change every tax year. Our support packages cover those updates so your calculations and RTI submissions stay correct. You own the code, so you're never forced into an upgrade you didn't ask for.
Can you integrate with our accounting and time-tracking systems?
Yes. We commonly connect payroll to Xero, QuickBooks and Sage so wages, tax and pension costs post to the general ledger without rekeying, and to time and attendance tools so hours, shifts and overtime flow through automatically. For compliance-critical payroll data we build proper API integrations with logging rather than relying on brittle webhook tools.
What about data security and compliance?
Payroll data is personal data, so UK GDPR applies fully. Systems include encryption, role-based access, and a complete audit trail of who changed what and when. We build to HMRC record-keeping rules, including the six-year retention expected for payroll and pension records, and design for RTI Full Payment Submissions on or before payday.
When is off-the-shelf payroll software the better choice?
If your payroll is straightforward, salary plus overtime and standard deductions, on a single UK entity with normal RTI and auto-enrolment needs, a recognised SaaS product is usually enough and we'll tell you so. A custom build earns its place when you have complex commission or variable pay, multi-entity consolidation, unusual approval or audit requirements, integrations SaaS doesn't support, or a headcount large enough that per-employee pricing has become painful.
Do you provide training for our team?
Yes. We train the finance team on running payroll, HR on employee data and absence, and approvers on sign-off and audit review, usually a couple of hours per role. You get written documentation and quick-reference guides, plus refresher sessions when you need them.