What Makes Business Expense Apps Cost More or Less?

A logistics company running a fleet of 45 delivery vehicles across the UK was spending around £3,200 every month on fuel alone, but they had no clear way to track which drivers were filling up where, whether the amounts matched their routes, or if anyone was submitting duplicate receipts. They needed an expense management solution but had quotes ranging from twelve grand all the way up to ninety-five thousand pounds, and the difference between those numbers wasn't clear at all. The features listed looked similar, the timelines seemed comparable, and yet the prices were miles apart.

The cost of building an expense management app depends less on what you build and more on how many edge cases you need to handle

What you're paying for when you commission a business expense app isn't just the time it takes to write code and design screens... you're paying for decisions about data handling, security protocols, integration complexity, and the number of different scenarios the app needs to manage without breaking. A simple expense tracker that lets people photograph receipts and categorise spending might take six to eight weeks to build and cost somewhere between £8,000 and £15,000. An app that needs to integrate with your accounting software, handle multi-currency transactions, enforce approval workflows, and comply with HMRC reporting requirements could easily run to £60,000 or more. The difference isn't padding or profit margins, it's the actual work involved in making those systems talk to each other properly and handling all the ways things can go wrong.

Why Some Expense Apps Cost £10K While Others Cost £100K

The simplest expense apps are really just digital notebooks with a camera attached. You take a photo of your receipt, type in the amount, pick a category from a list, and submit it for approval. That's about two weeks of design work and four to five weeks of development time if you're building for one platform, which puts you somewhere around the ten to twelve grand mark for a basic but functional solution.

Apps at the higher end are doing something completely different. They're parsing receipt data automatically using optical character recognition, validating expenses against company policies in real time, syncing with your payroll system, handling different tax rates depending on location, managing corporate card transactions, and generating reports that feed directly into your accounting software. Each of those capabilities requires its own development time, testing, and maintenance plan.

The other factor that drives costs up is user experience refinement. A simple app might show you a list of expenses and let you tap through to see details. A more expensive solution will have spent time on making the approval process feel natural, reducing the number of taps needed to submit an expense, handling offline scenarios gracefully, and making sure the app doesn't become frustrating to use when you're trying to claim expenses while standing in a taxi queue at the airport. That polish takes time, and time costs money.

The Features That Actually Drive Up Development Costs

Receipt scanning is where most apps start, but the quality of that scanning makes a huge difference to your budget. Basic photo capture is straightforward... you take a picture, it saves to the app, done. Text recognition that can pull out the merchant name, date, and total amount needs OCR libraries and quite a bit of work to handle all the different receipt formats you'll encounter. We built an expense app for a professional services firm where the receipt scanning had to handle everything from printed restaurant bills to handwritten taxi receipts to emailed confirmations from airlines, and that variety meant building in multiple fallback methods and manual correction workflows.

If your budget is tight, start with manual entry and add automated receipt scanning in a later update once you've proven the app gets used regularly. The scanning feature alone can add £8,000 to £12,000 to your project cost.

Approval workflows sound simple until you map out how they actually work in your organisation. If expenses under fifty quid get auto-approved but anything over that needs manager sign-off, and expenses over two hundred pounds need finance approval as well, and expenses submitted on the last day of the month follow different rules, you're looking at quite a bit of business logic that needs to be coded, tested, and made visible to users so they know what's happening with their claims.

• Multi-currency conversion with live exchange rates adds £4,000 to £7,000
• Policy violation detection and warnings adds £3,000 to £6,000
• Corporate card transaction matching adds £5,000 to £9,000
• Mileage tracking with GPS route verification adds £6,000 to £11,000
• Offline mode with sync conflict resolution adds £4,000 to £8,000

Reporting and analytics capabilities can range from basic CSV exports that cost a few hundred pounds to implement, all the way through to custom dashboard views with drill-down capabilities, trend analysis, and automated anomaly detection that might add twenty grand to your project. The question you need to answer is whether those insights will actually get used or whether a simple monthly summary sent by email would do the job just as well.

Building For One Platform vs Multiple Platforms

If everyone in your company uses iPhones then building just for iOS will save you a considerable amount compared to supporting both iOS and Android. A single-platform app typically costs about 40% less than a cross-platform solution, though that gap has narrowed as cross-platform tools have matured.

Native vs Cross-Platform Development

Native development means building separate codebases for iOS and Android, which roughly doubles your development time and budget. The advantage is that you get apps that feel completely at home on each platform and can take advantage of the latest features as soon as they're released. Cross-platform frameworks let you write most of your code once and deploy to both platforms, which saves money upfront but can create complications when you need to access platform-specific features or optimise performance.

Web apps that run in mobile browsers have become more capable but they still can't match native apps for camera access, offline functionality, and overall responsiveness. For an expense app where people need to quickly snap a receipt and move on with their day, that performance difference matters quite a bit, which is why most serious expense management solutions are proper native or cross-platform apps rather than mobile websites.

When Your Expense App Needs Custom Integrations

The integration question is where budgets often expand beyond initial estimates because the complexity isn't obvious until you start mapping out data flows. Connecting your expense app to Xero or QuickBooks sounds straightforward, and if you're just pushing expense totals once a week then it is... that might cost £3,000 to £5,000 to implement properly. But if you need two-way sync where changes in your accounting system update the app and vice versa, with proper conflict resolution and error handling, you're looking at more like £8,000 to £15,000.

Every integration point is a potential failure point, so you need to budget not just for building the connection but for monitoring it and handling the inevitable API changes over time

We worked on a finance app for a property management company that needed to connect with their existing CRM, their accounting software, their HR system for employee data, and their banking provider for corporate card transactions. Each integration had its own API documentation (or lack thereof), its own authentication requirements, its own rate limits, and its own quirks that needed to be worked around. What started as a £40,000 project ended up closer to £65,000 once we'd properly scoped all the integration work.

Common Integration Points and Their Costs

Banking APIs for transaction imports run from about £6,000 to £12,000 depending on which banks you need to support and whether you're using an aggregation service or connecting directly. HMRC's Making Tax Digital APIs for VAT reporting add another £5,000 to £9,000 if you need that level of compliance. Payroll system integrations vary wildly depending on what you're using... something like BreatheHR or CharlieHR has decent API documentation and might cost £4,000 to integrate, whereas older payroll systems might need custom export scripts and could run to fifteen grand or more.

The other consideration is what happens when those integrations break. APIs change, authentication methods get updated, rate limits shift, and you need someone who can fix things when they stop working. That ongoing maintenance is separate from your initial build cost but needs to be factored into your total budget for running an expense app.

How User Numbers Affect Your Budget

Building an app for twenty users versus building one for two thousand users doesn't change the interface design much, but it changes a lot about how the backend systems need to be architected. With a small team you can get away with simpler database structures, less aggressive caching, and fewer optimisations. You might spend £12,000 on an app that works perfectly well for fifty employees submitting maybe two hundred expenses per month.

Scale that up to five hundred employees submitting three thousand expenses monthly and you need to think about database indexing, API response times, image storage costs, and what happens when everyone tries to submit their expenses on the last day of the month. Those infrastructure considerations might add £6,000 to £10,000 to your build cost, plus higher ongoing hosting fees once the app is live.

Performance matters more than people think. If your expense app takes eight seconds to load or if the camera crashes every third time someone tries to photograph a receipt, people will stop using it and go back to email and spreadsheets. We've seen that happen. Optimising for performance, especially with image-heavy apps where people might be uploading dozens of receipt photos, takes time and testing across different devices and network conditions.

The other user-related factor is admin functionality. An app for a small team might have minimal admin features... maybe just a basic web dashboard where someone can export expense reports. An app for a larger organisation needs user management, department hierarchies, role-based permissions, custom approval workflows, policy configuration, and detailed analytics. That admin panel can easily cost as much to build as the mobile app itself.

The Real Cost of Receipts and Document Processing

Receipt management is more complicated than it looks. You're not just saving an image... you're capturing data from that image, storing it securely, making it searchable, ensuring it meets record-keeping requirements, and eventually archiving or deleting it according to retention policies. HMRC requires businesses to keep records for at least five years, which means your receipt storage solution needs to be reliable and backed up properly.

Budget for image compression and cloud storage costs from day one. An app with 200 users each submitting 10 receipt photos monthly generates about 24,000 images per year, which can cost £150-300 annually in storage fees alone.

OCR and Data Extraction

Optical character recognition services charge per image processed, typically between 1p and 3p per receipt depending on volume. That might not sound like much but it adds up... if you're processing five thousand receipts monthly you're looking at £50 to £150 per month just for the text extraction. Some of those services also charge for API calls, data storage, or additional features like automatic categorisation or fraud detection.

The build cost includes integrating the OCR service, handling errors when text can't be read properly, building the correction interface for when the automatic extraction gets things wrong, and testing across hundreds of different receipt formats. Receipts vary enormously... thermal receipts fade, handwritten receipts have unclear writing, emailed receipts come in PDF format, and international receipts use different date formats and currencies.

Security Requirements That Change Everything

Financial data requires proper security, which means encryption at rest and in transit, secure authentication, regular security audits, and compliance with data protection regulations. Those requirements add both time and cost to your project, but they're not optional... the last thing you want is to build an expense app that leaks employee financial information or makes it easy for someone to commit fraud.

Basic security measures like HTTPS connections, password hashing, and session management are standard practice and don't add much to your budget. More sophisticated requirements like biometric authentication, end-to-end encryption, or penetration testing can add anywhere from £4,000 to £20,000 depending on what you need to prove to your information security team or your auditors.

Compliance and Audit Requirements

If you're handling personal financial data (which you are with an expense app), you need to comply with GDPR and that means building in data export functionality, deletion capabilities, consent management, and detailed logging of who accessed what data when. Those compliance features might add £5,000 to £8,000 to your project but they're not negotiable unless you want to risk substantial fines.

• Two-factor authentication adds £2,000 to £4,000
• Biometric login (fingerprint, face recognition) adds £1,500 to £3,000
• End-to-end encryption adds £4,000 to £8,000
• Security audit and penetration testing adds £3,000 to £12,000
• SOC 2 compliance preparation adds £8,000 to £25,000

We built a spending app for a financial services company that needed to pass their security review before it could be approved for internal use. That meant implementing certificate pinning, adding additional logging, encrypting data in the local database, and providing detailed documentation about how we handled sensitive information. The security requirements added about three weeks to the project timeline and roughly eleven grand to the budget, but there was no way around it given the regulatory environment they operated in.

Maintenance and Updates Nobody Tells You About

The build cost is just the beginning. Every year Apple and Google release new versions of their operating systems, and apps need to be tested and updated to make sure they still work properly. That testing and updating typically costs about 15% to 20% of your original build cost annually... so if you spent £30,000 building your expense app, you should budget £4,500 to £6,000 per year just to keep it running without adding any new features.

Apps aren't like websites where you can update them once and everyone sees the changes immediately. Users need to download updates, which means you're often supporting multiple versions of your app running in the wild simultaneously

Bug fixes happen. Despite proper testing, issues emerge once real users start doing things you didn't anticipate. Someone tries to submit an expense while their phone switches from WiFi to mobile data and the app crashes. Someone photographs a receipt in direct sunlight and the automatic text extraction fails completely. Someone's manager leaves the company and their pending expenses get stuck in approval limbo. Each of those scenarios needs to be fixed, tested, and released as an update.

Ongoing Costs Beyond Development

Server hosting for an expense app with a few hundred users typically runs £80 to £200 per month depending on your hosting provider and how much data you're storing. Add another £30 to £100 monthly for OCR processing fees if you're using automatic receipt scanning. Third-party service fees for things like authentication, analytics, crash reporting, and push notifications might add another £40 to £150 monthly. Those recurring costs matter... over three years you might spend £8,000 to £15,000 just on keeping the lights on.

Feature requests will come in once people start using the app. Can we add mileage tracking? Can the app remember my favourite expense categories? Can we integrate with our new accounting system? Some of those are quick changes that take a day or two, others are substantial features that might cost £3,000 to £8,000 to implement properly. Having a budget set aside for enhancements means you can make the app more useful over time rather than letting it become outdated and frustrating. Understanding the difference between bug fixes and new features helps you plan these updates properly.

Conclusion

The cost of building an expense management app depends on how many problems you're trying to solve and how polished you need the solution to be. A basic receipt tracker with manual entry and simple reporting might cost £12,000 to £18,000 and take eight to ten weeks to build. A full-featured expense management system with automated receipt scanning, policy enforcement, multiple integrations, and detailed analytics could easily run to £60,000 or more and take four to six months from discovery through to launch.

The mistake companies make is trying to build everything at once. Start with the core features that solve your biggest pain points, get people using the app, and then add capabilities based on what you learn from actual usage patterns. That approach spreads your costs over time and means you're not spending fifteen grand on features that nobody ends up using. The other advantage is that you can prove value early... if your simple expense app saves your finance team ten hours per month on processing claims, that's a clear return on investment that justifies expanding the budget to add more sophisticated features.

Testing matters more than most people realise. An expense app that crashes regularly or loses data won't get used no matter how many features it has. Budget for proper quality assurance, test with real users before launch, and plan for a few weeks of refinement after launch based on feedback. That testing time is worth every penny because it's much cheaper to fix problems before thousands of people are trying to use your app to claim their business expenses.

If you're trying to work out what your expense management app might cost and need someone to help you think through the features, integrations, and ongoing costs, get in touch and we can walk through your specific requirements.

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