Managing expense reimbursements at scale: challenges and best practices

Updated: July 2026

Expense reimbursement is when a company pays employees back for out-of-pocket purchases made on behalf of the company. In large enterprises with multiple entities, that simple definition hides a lot of complexity, and it is worth being clear about why reimbursement becomes so difficult at scale.

• Large enterprises have a high volume of employees who need to be reimbursed, which means many transactions and a lot of documentation to keep track of.

• Different entities and departments often run different reimbursement policies, approval processes, and accounting systems, and those inconsistencies create mistakes and delays.

• Frequent travellers struggle to manage receipts, track expenses, and stay aligned with both company policy and local tax regulations.

• Bigger companies carry stricter rules and audit requirements to prove they are following regulations, and that adds another layer of oversight to every claim.

Because of these pressures, some organizations hesitate to automate reimbursement at all. They worry that automation will make the process more complicated or reduce their control over it. The opposite is true. This article looks at how large companies can tackle these challenges, and it shares the best practices that make reimbursement faster and more accurate while keeping you fully compliant across every jurisdiction you operate in.

Most common types of reimbursable expenses

Reimbursable expenses fall into a handful of recurring categories, each with its own rules for documentation, tax treatment, and how you actually pay the money back. Getting these categories straight is the foundation for a clean policy and a process that automates well, so let's clarify them before looking at the challenges.

Travel expenses

Travel expense reimbursement covers the broad range of costs employees incur while traveling for work, from airfare, train tickets, public transport, and taxi fares through to accommodation, meals, and other incidental costs. Because these categories differ in how they are taxed and documented, most companies define them explicitly in policy rather than lumping everything under a single "travel" line.

One distinction matters early on. Costs tied to using a company or personal vehicle are usually handled separately from general travel expenses, and we cover those in the next section.

Mileage reimbursement

Mileage reimbursement compensates an employee for the distance driven in a personal or company vehicle on business, and in most countries this counts as a legitimate business expense. Although both mileage and general travel reimbursement cover the cost of getting from A to B, the difference is that mileage reimbursement focuses specifically on distance driven rather than tickets or fares.

The amount is usually based on a standard mileage rate set by the organization or the local government, and beyond fuel it can also account for maintenance and vehicle depreciation. There are two common ways to calculate it.

• The fixed rate method is the most common. You multiply the distance travelled by a set rate per kilometre or mile, so every mile is reimbursed at the same rate regardless of circumstance. For example, a company might apply a flat rate of $0.50 per mile.

• A complex rate factors in variables such as vehicle type, fuel prices, and maintenance costs, so the rate can vary by vehicle or trip purpose. A company might reimburse electric vehicles at a higher rate and older, less efficient vehicles at a lower one.

The trade-off is straightforward. Fixed rate is simpler to administer but ignores specific circumstances, while complex rate is more tailored but requires more calculation and record-keeping. Rates also change by jurisdiction, which is exactly the kind of moving detail that AI-powered expense management software keeps current in the background so finance teams never apply an outdated figure.

Meal reimbursements

Meal reimbursements cover food costs employees run up on business trips or during long working hours, typically at restaurants, cafés, or hotels, and the way you pay them back depends on your policy and local regulation. Broadly, there are two approaches. Some companies provide a per diem allowance to cover meals while an employee is travelling, which removes the need to track individual receipts. Others reimburse the actual cost up to a spending limit, in which case employees must keep and submit receipts alongside their expense reports.

Policies often restrict what qualifies. Expensive meals, or meals with alcohol, may be excluded, and in those cases employees usually need prior approval or a documented reason for any overspend. Whatever rules you set, you still need to follow local tax law and keep clean records that prove the expense was genuinely for business, which becomes essential the moment an audit lands.

Lump sums / per diem allowances

A per diem, Latin for "per day", is a fixed daily amount an employee receives to cover meals, accommodation, and incidental expenses while travelling for business, and it is the single best way to manage daily allowances at scale because it removes receipt-level tracking entirely. The rate is set by the location the employee is travelling to and is meant to cover reasonable costs for the day, which gives you a simple, consistent, and predictable way to reimburse people.

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The best-run per diem programs share a few characteristics. They anchor rates to official government benchmarks, apply clear rules for partial travel days and provided meals, and keep documentation light while remaining audit-ready. The table below summarises the practices that separate a smooth per diem system from one that creates friction.

If an employee has already had a meal paid for, for instance breakfast included in the room rate, that portion should be deducted from the allowance for the day. Set at a sensible level, per diems simplify the whole process, remove the burden of tracking individual expenses, and can even generate savings when the daily rate sits below what employees would otherwise spend.

The catch is that per diem calculation, deduction logic, and tax treatment differ from one country to the next, and doing this by hand is where errors creep in. Perk's expense management solution calculates and applies per diems and allowances automatically based on predefined rules for each entity and destination, which keeps reimbursements accurate and consistent even across a large, multi-country workforce. For a deeper walkthrough, our guide to per diem allowances for business travel and our per diem calculator show exactly how the numbers work.

Receipt expenses

Receipt expenses are the most common type of all: an employee submits a receipt for a single purchase and gets reimbursed for it. These are not limited to business trips. Office supplies, a team lunch, or any one-off cost that does not belong to a wider trip all fall into this category, and they are the easiest expenses to automate because the receipt itself carries most of the data your system needs.

Challenges in the employee expense reimbursement process

Now that the expense types are clear, it helps to name the specific problems large companies run into when reimbursing employees, because each one maps directly to a fix later in this article. The friction almost always traces back to four sources: manual effort, missing visibility, fraud risk, and sheer volume.

Manual, time-consuming process

The manual expense reimbursement process consumes significant time and money, because paper receipts, manual data entry, and spreadsheet tracking create bottlenecks and errors at every step. According to PayStream Advisors, 47% of companies still rely on manual or paper-based expense management. Research from the Global Business Travel Association (GBTA) puts the cost of that approach in stark terms: processing a single expense report manually takes about 20 minutes and costs roughly £45, with a 19% error rate that then needs correcting. Those delays slow reimbursements, frustrate employees, and pull finance teams away from work that actually matters.

Lack of visibility and control

Without a centralized tracking system, finance teams cannot monitor spending in real time or enforce policy effectively. When the process depends on employees submitting receipts after the fact, finance is always looking backwards. That makes it hard to set and enforce limits, difficult to track spend as it happens, and almost impossible to guarantee compliance with company policy, which leads directly into the next challenge.

Risk of error and fraud

Manual processes create openings for duplicate submissions, incorrect claims, and outright fraudulent expense reports that translate into real financial losses. The risk is sharpest in large companies with multiple entities, especially where employees are spread across countries with different tax rules, because non-compliance carries both legal and financial consequences. Policy breaches take familiar forms: a receipt submitted twice, a per diem claimed at the wrong rate, spend above a limit, or a purchase that simply does not qualify under the reimbursement policy.

With spend management software like Perk, the platform detects duplicate submissions, flags likely fraud and policy breaches, and calculates per diems automatically based on the relevant entity. Because the AI validates every submission before it moves forward, the errors that human reviewers miss are caught at the point of submission rather than weeks later.

Complexity due to volume

High transaction volumes overwhelm finance teams, which pushes up both processing delays and error rates. As a company grows, its policies and approval chains grow more intricate, and that makes it harder for employees to submit correctly and on time. The rising volume of expense reports turns reimbursement into a resource-intensive grind, and the more manual it stays, the more mistakes slip through. The practical fix is to standardise policy and adopt expense management tools that reduce the workload for finance teams while making submission easier for everyone else.

Manual vs. automated expense reimbursement comparison

The gap between a manual process and an automated one is not marginal, it is an order of magnitude. The table below sets the two side by side on the measures finance leaders care about most.

Best practices for automating the expense reimbursement process

With the expense types and challenges clear, here are the practical steps that make reimbursement faster, cheaper, and more compliant. The sequence matters: understand your process, clarify your rules, then automate on top of both. This is also where the biggest single lever sits for finance leaders asking how to reduce reimbursement processing time. Automation, embedded policy, and fewer out-of-pocket claims are what take a cycle from weeks down to days.

1. Map the process

The first best practice is to map the reimbursement process end to end, documenting every step from submission through approval to payment. Mapping shows you where the inefficiencies sit and where automation will deliver the most value, so it is worth doing before you change anything else.

Start by identifying every stakeholder, then document what each of them actually does today.

• An employee's process might involve capturing a receipt or invoice, filling out an expense report, and submitting it to their manager for approval.

• A manager's process might involve reviewing and approving the report, forwarding it to finance, and giving feedback to the employee where needed.

• The finance team's process might involve checking the expense against company policy and local regulation, extracting VAT, reimbursing the employee, and booking the reimbursement into the accounting system.

Laying it out in this detail shows you exactly how each step is handled and where you can eliminate, automate, or streamline it. Almost always, the mapping exercise reveals steps that add no value and can simply be removed.

2. Clarify the internal policies, rules and regulations

The second best practice is to clarify your internal policies, rules, and regulations, which means defining clear expense policies that every employee can understand. Spell out which expenses qualify, the maximum reimbursable amount per category, and the documentation or approvals required. A well-drafted expense reimbursement policy removes the ambiguity that causes late, incorrect, and rejected claims.

Tax and regulatory requirements are just as important, and they are where cross-border reimbursement gets genuinely difficult. You need to know which expenses are taxable, how VAT is handled, and what local rules apply in each country you operate in. The variation is significant, as these examples show.

This is exactly why managing reimbursements in different countries becomes a headache when it is manual. Finance has to calculate lump sums, cross-check local regulations against internal policy, handle multiple currencies at the right exchange rate, and separate taxable from non-taxable items, all before paying anyone. The way to manage cross-border reimbursement without that risk is to standardise one global policy with local rules layered on top, then let software enforce the local variation automatically. Perk applies jurisdiction-specific per diem rules, multi-currency spend, and local mileage and VAT rates in the background, converting expenses at the transaction date and flagging anything non-compliant before it reaches an approver. That combination is what keeps a global, multi-entity reimbursement program both fast and audit-ready.

3. Automate the expense reimbursement process

Mapping shows you the current state, and clear policy defines the rules, so the third best practice is to automate on top of both. With a spend management platform like Perk, every stage below can be automated, and this is where processing time collapses from days to minutes.

Expense submission

In a traditional process, an employee collects paper receipts, photographs or scans them, and either uploads them to a tool, records them in a spreadsheet, or emails them to finance. None of that happens in real time, which delays the books and often leaves finance without a clear reason for any overspend.

With a platform like Perk, the submission phase can be fully automated. Employees submit on time, finance gets a complete view of every report, and any overspend, along with its justification, is recorded permanently, which is invaluable during an audit. Better still, when employees pay with Perk smart corporate cards instead of private cards, transactions reconcile against receipts in real time. That gives finance full visibility, prevents policy breaches, and lets the system catch duplicate receipts and warn users about out-of-policy spend as it happens. Even with traditional corporate cards, employees can snap or upload a receipt in the app and let the platform match the transaction automatically. Data is read in real time, the AI categorises each item, reconciliation runs on its own, and a finished report is one click away from approval, all in seconds.

Approval workflow

Once expenses are submitted, approval begins, and in a manual process this can take anywhere from minutes to hours depending on the complexity involved. With Perk, you can automate it through auto-approval workflows: set a threshold, and any compliant expense below it is approved automatically unless the AI detects a policy breach or duplicate. If it does spot an outlier, duplicate, or potential fraudulent expense, the report is sent back for revision or rejected. Routing compliant claims straight through and reserving human attention for genuine exceptions is one of the fastest ways to cut turnaround time.

Policy enforcement

Enforcing compliance is one of the most time-consuming parts of a manual process, and one of the easiest to automate. With Perk, all your rules and policies are configured once, and the AI validates every submission at both the organization level and the individual legal-entity level, so no one has to manually hunt for anomalies. Unless an outlier appears, human involvement is minimal, and even then the work is straightforward because the tool flags the specific breach so the employee can correct the report themselves. Where a legitimate exception exists, for example an overspend on a client dinner, employees can add a reason so the claim is reviewed rather than rejected outright.

Reimbursement and reporting

Once expenses are reviewed, approved, and exported to the finance system, reimbursement runs automatically and employees get paid promptly, which is the whole point of the exercise. On top of that, Perk lets finance teams generate real-time reports on spending patterns across whatever fields matter to them, surfacing both cost-saving opportunities and process inefficiencies. That reporting layer is also where you spot whether your per diem rates or reimbursement plans need adjusting.

Best practices checklist

1. Document all stakeholders in your reimbursement workflow before implementing automation.

2. Set automated spending thresholds for approvals based on expense category and employee level.

3. Configure AI-powered duplicate detection to flag receipts submitted more than once.

4. Establish clear per diem rates aligned with local government requirements for each country of operation.

5. Integrate expense management software with your ERP system for seamless data flow.

6. Create exception handling procedures for legitimate policy overrides with required documentation.

7. Schedule regular audits of automated rules to keep pace with changing regulations.

Use smart corporate cards for full visibility

The final best practice is the most effective way to cut reimbursement processing time: reduce the number of reimbursements you handle at all. Replacing out-of-pocket spend and private cards with smart corporate card payments gives finance full visibility and better control, and it removes the reimbursement queue for most everyday spend because the company pays directly.

A smart corporate card is more than a typical corporate credit card. It works like an ordinary card across debit, credit, or prepaid methods, but it is integrated with financial software to deliver data-driven insight and advanced controls.

In practice, that means real-time expense management, automated accounting and reconciliation, stronger security controls, and a cleaner experience for cardholders. Smart corporate cards use machine learning, AI, and data analytics to catch transactions the moment they happen, match them to receipts automatically, and enforce spending limits at the point of purchase. For cross-border teams, they also handle multi-currency transactions and consolidate everything into a single view, which is why they are the cleanest answer to managing reimbursements across different countries. Perk customers who add spend management alongside travel see a 79% reduction in expense processing costs and a 5.5x return on investment, and DO & CO achieved a 550% ROI after combining Perk's smart cards with its expense management tool.

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