Payroll software is one of those things businesses tend to settle for. You pick a package, twist your workflows around it, pay the monthly fee, and put up with the bits that don’t quite fit. After a few years, the subscription cost quietly becomes one of your bigger line items, and the system still doesn’t do that one thing you’ve been asking about since month two.
We build custom payroll systems instead. Yours, not rented. Designed around the way your team actually runs payroll, with the integrations you need and the reporting you’ve been doing in spreadsheets because the SaaS tool wouldn’t.
We’re based in London, so HMRC quirks aren’t exotic to us: RTI submissions, auto-enrolment, CIS, the apprenticeship levy, term-time pay, NHS pension schemes, student loan plans, statutory sick and maternity pay. If you’re a UK business and your payroll software has become a tax on your finance team’s time, this is the conversation worth having.
Why off-the-shelf payroll software keeps disappointing UK businesses
The UK payroll software market is large, cloud-dominated and crowded. For a single-entity business with standard pay, stable headcount and no awkward approval rules, a SaaS product is usually the right call, and we’ll tell you so. The trouble starts when your payroll stops being standard. A few patterns come up almost every time we sit down with a finance director:
- The software dictates the workflow, so people end up doing extra steps to keep it happy
- Approval chains are hardcoded. There’s no clean way to say “anything over this amount needs the CFO” or to route sign-off by cost centre
- Commission, bonuses, retro-pay, reversals and one-off deductions live in spreadsheets because the platform assumes everyone is salaried or hourly
- Per-employee pricing scales badly. At 100-plus staff the renewal quote often lands as a genuine shock
- Connecting it to your accounting package, HR system or time-and-attendance kit turns into a project of its own, and the payroll-to-ledger posting still lags or duplicates
- Several popular platforms aren’t HMRC-recognised in the UK, so RTI ends up needing a bridge or manual workaround
- HMRC changes the rules and the vendor’s update lands later than you’d like
The licence fee is usually the smallest part of the cost. The bigger one is the manual work that builds up around the software’s gaps, and the time your finance team spends apologising for them. Implementation, data migration and integration fees frequently exceed the headline subscription, and they rarely appear on the pricing page.
A custom build earns its keep when the awkwardness is real and ongoing: non-standard pay structures, approval rules tied to your governance, multiple legal entities, tight integration with a finance system you can’t easily replace, or data residency constraints. If that sounds like you, read on.
What changes when payroll is built for you
Our UK team builds payroll systems around your actual process, not a generic one.
Designed around how you work
We spend the first couple of weeks watching your payroll run, asking awkward questions, and mapping what already works. The software then supports those habits rather than replacing them. Crucially, your approval workflow can match your org chart, not the other way round.
Pay once, own it
You commission the system, we build it, you own it. No per-employee monthly fees ticking up as you grow, no minimum contract term, no early-exit penalty, and no data trapped in a proprietary format if you ever want to move on. The code is yours.
Built to talk to your other systems
Xero, Sage, QuickBooks, your HR platform, time-and-attendance kit, your bank’s BACS files - we wire it all up so data only gets entered once. Payroll posts straight to the general ledger with the journal structure your accountants actually use, so the reconciliation work most teams dread mostly goes away.
HMRC compliance handled
PAYE, National Insurance, RTI submissions (Full Payment Submission and Employer Payment Summary), pension auto-enrolment including the three-year re-enrolment cycle, P45s, P60s, P11Ds, CIS, the apprenticeship levy where it applies. The system files what it needs to file, in HMRC’s required format. When legislation changes, we update it.
Built to scale with you
Add a new entity, a new pay structure, a new bonus scheme, eventually a new country - it’s a configuration change or a small build, not a forklift upgrade. Per-employee pricing doesn’t punish you for hiring.
Support from people you can actually reach
Our team is in London. When something needs sorting, you get a developer who knows your system, not a tier-one script reader working through a queue during the busiest week of the tax year.
What a typical custom payroll system includes
Every build is shaped around your requirements. We usually ship a working core first, then add the rest in a second phase once it’s live and stable.
The core build covers:
- Gross-to-net calculation of salaries, tax, NI, pension contributions and statutory deductions, driven by each employee’s tax code and NI category
- Configurable salary structures and pay rules, including conditional and project-linked deductions
- Batch payroll runs - weekly, fortnightly, monthly - with clear status tracking through draft, approved and paid
- BACS payment file generation and payslip distribution
- Direct HMRC filing for RTI, plus P45s, P60s and P11Ds
- Approval workflows that match how authorisation actually happens, including conditional sign-off by amount or cost centre
- General-ledger posting into your accounting package, with reconciliation reports
- Audit trails and role-based, UK GDPR-compliant data handling
A second phase commonly adds:
- An employee self-service portal for payslips, leave requests and personal detail updates
- Time-and-attendance integration so hours feed payroll without manual rekeying
- Multi-entity payroll for groups running several companies or subsidiaries
- Commission and bonus calculation pulled from sales or performance data
- A finance dashboard - payroll cost trends, headcount, overtime patterns, tax liability
- Mobile access for approvals and reporting
How we build it
Discovery and planning, two to three weeks
We sit with your payroll team, your finance lead, and whoever owns the integrations. We document the current process, the friction points, the bespoke deductions hiding in spreadsheets, and what good looks like. You get a written spec and a fixed quote.
Build, six to twelve weeks
Our developers in the UK do the work. We show you progress every couple of weeks, you push back on the bits that don’t feel right, we adjust. We build the core payroll engine first so there’s something real to test against.
Migration, testing and rollout, two to four weeks
Migration is the part that catches most projects out. Year-to-date balances, historical payroll, employee master data, deductions and leave balances all have to come across cleanly, and legacy data rarely is. We audit and cleanse it, reconcile year-to-date totals against your ledger, then run the new system in parallel with your existing one until the numbers match exactly. Only then do we cut over - never on the Friday before a bank holiday.
Training and support
We train your team in person or remotely, document everything, and stay on call after go-live. Payroll staff need the most hands-on time; managers approving runs need an hour or two. After the included support period, ongoing support is optional.
Most single-entity projects run three to six months end to end. Multi-entity payroll, heavy integrations or unusual pay structures push that out.
What it costs, honestly
Custom development costs more up front than signing up to a SaaS product. The maths only works if you’re going to keep the system for a few years, which most businesses do.
For context: per-employee SaaS payroll typically runs a base fee plus a charge per head per month, which is fine at small scale but compounds badly. At 100-plus staff the annual figure becomes substantial, every year, and you own none of it - and that’s before setup, migration, integration and tax-filing fees, which often don’t show on the pricing page. For a single-entity UK payroll with standard pay structures, RTI, GL integration and basic approval workflows, custom builds typically land between £40,000 and £100,000. Multi-entity or multi-jurisdiction systems with complex pay rules run higher.
What you get back:
- Less time lost to payroll admin once calculation, RTI and GL posting are automated
- Fewer calculation errors and fewer reconciliation mismatches
- No more “we’d need to upgrade your plan for that” conversations when you want a new feature
- No per-employee pricing penalty as you grow, and no multi-year lock-in
- A piece of software that’s actually yours, code included
We quote the real number after the discovery phase. No tiered pricing games, and if SaaS is genuinely the better-value choice for your situation, we’ll say so.
Sectors and situations we build for
The pattern of “off-the-shelf doesn’t quite fit” looks slightly different in each industry, but it’s everywhere:
- Construction handling CIS returns, subcontractor payments and payroll allocated to project codes for accurate job costing
- Healthcare and social care with rotating and on-call shift patterns, on-call premiums, NHS pension schemes and cost allocation across wards or care homes
- Hospitality and retail running high-volume, variable-hour rotas, split shifts and tip distribution
- Manufacturing tying payroll to time-and-attendance and production data, including shift premiums and piece-rate pay
- Education with term-time-only contracts, variable hours and research-grant cost allocation
- Professional and financial services with mixed employee and contractor payments, partner draws, profit-share and variable compensation
- Charities allocating payroll across restricted funding streams and grants
- Tech companies going from ten staff to a hundred-plus without changing systems, often with contractors alongside permanent staff
Common trigger points: manual payroll has crept past ten to fifteen hours a pay run; you’ve added a second legal entity; an RTI error or HMRC enquiry has exposed a control gap; payroll and your accounts have drifted out of sync; or your payroll specialist has left and taken the undocumented process with them.
If your situation is awkward enough that the standard tools never quite fit, that’s usually the signal that a custom build will pay back.
Common Questions About Custom Payroll Management Systems
How does a custom payroll build compare on cost to SaaS?
A custom build costs more up front. The trade-off is that you stop paying per-employee fees that never end. For a single-entity UK payroll with standard pay structures, RTI submission and accounting integration, builds typically land between £40,000 and £100,000. Complex multi-entity or multi-jurisdiction systems run higher. Whether it pays back depends on your headcount and how badly off-the-shelf software fits, which is something we work through honestly during discovery rather than promising a fixed break-even date.
What's the typical development timeline?
Most single-entity builds run three to six months from first conversation to go-live. We usually ship a working core first - calculation, RTI, payslips, GL posting - then add self-service, time-and-attendance integration or advanced reporting in a second phase. Multi-entity payroll, time-and-attendance integration or unusual pay structures push the timeline out.
Will the system handle HMRC RTI and pension auto-enrolment?
Yes. RTI is non-negotiable for UK employers, so Full Payment Submissions and Employer Payment Summaries are built to HMRC's required format, along with P45s, P60s and P11Ds. Pension auto-enrolment is handled end to end, including assessment, contributions and the three-year re-enrolment cycle. Where relevant we also cover the apprenticeship levy, student loan plans and statutory sick, maternity and paternity pay.
Can you integrate with our accounting and time-tracking systems?
Yes. We commonly wire payroll into Xero, Sage, QuickBooks and other accounting packages so payroll posts straight to the general ledger, plus HR systems, time-and-attendance tools and your bank's BACS payment files. The aim is that data is entered once and the month-end reconciliation most finance teams dread mostly disappears.
What happens with annual tax changes and ongoing support?
We include a support period after go-live and update the system when legislation changes - NI thresholds, tax codes, minimum wage rates, pension contribution rules. After that, ongoing support is optional and can be an annual arrangement or ad-hoc work as you need it. Because you own the code, you are not waiting on a vendor's release schedule when HMRC changes the rules.
How do you handle data security and GDPR?
Payroll data is some of the most sensitive your business holds - bank details, tax codes, National Insurance numbers. Systems are built with role-based access, encryption in transit and at rest, and full audit trails of who changed what and when. We can deploy on UK or EU infrastructure where data residency matters, and you remain the data controller with no ambiguity about where records sit.
Can you migrate our existing payroll data?
Yes, and we treat it as the riskiest part of the project. Year-to-date balances, historical payroll, employee master records, deductions and leave balances all have to come across cleanly. Legacy data is rarely tidy, so we budget time for cleansing and reconciliation, and we run the new system in parallel with your old one until the numbers match exactly before cutover.