Inside Airwallex's budgeting playbook: a Q&A with financial controller Ralph Karsten

Budgeting season. For many finance leaders at high-growth tech companies, it's the most challenging and critical period of the year. It's a high-stakes process of balancing ambitious growth targets with investor expectations, top-down goals with bottom-up needs, and long-term bets with short-term discipline.

To understand how a rapidly scaling global fintech navigates this, we sat down with Ralph Karsten, Financial Controller at Airwallex. He shares his insights on how the budgeting process has matured, how to manage the "standard budgeting game," and how finance can be a true enabler of growth.

Q: How do you define the budgeting season at Airwallex, and what’s the high-level timeline?

Ralph Karsten: We kick off in the back half of the year when we begin building the templates. The intensive cross‑functional alignment runs through late Q4.

We aim to have a final management‑aligned plan in Q4, with formal board review and approval before the end of the year to allow teams to start the new financial year strong. By the time it reaches the board, the executive team is aligned on both the plan and the narrative.

Q: What makes for a "great" budgeting season versus a "good enough" one?

RK: Clarity. In prior experience, ambiguous guardrails made planning chaotic. When bottom‑up asks arrive before clear top‑down targets, it’s hard to prioritise.

We're a lot better at setting those top‑down targets from the start. A "great" season is one where the top‑level goals (for growth and cash discipline) are clear, enabling productive, focused conversations about trade‑offs rather than debate over direction.

Three principles guide us: 1) Set clear guidance first. 2) Drive growth by capacity and unit economics, not wishlists. 3) Pre‑agree a short list of levers so decisions are fast when conditions change.

Q: How do you align those top-down targets with bottom-up plans from functional leaders?

RK: This is always the most complicated part of the budget. It usually flows like this:

1. Set the top‑down guidance: We start with a top‑line projection and controlled cost‑growth parameters.

2. Get the bottom‑up asks: We ask all divisions for their plans with details on what they want to spend on and why.

3. Prioritise the critical items: We lock in the most critical, revenue‑driving items first, which is often sales capacity and enablement tied to productivity milestones.

4. Negotiate: From there, we go division‑by‑division and ask, "Why is this needed? What are the alternatives? Is the timing of spend aligned with capacity to deliver?” If we see significant investment in a particular area, we review the ROI and take a strategic decision on whether we move forward with the spend."

It’s the standard negotiation. We set ambitious targets; teams request resources; we pressure‑test against productivity, timing, and alternatives, often landing on a stretch plan with fewer net‑new roles and clearer milestone gates.

Q: What key inputs do you lock in before setting those top-down targets?

RK: The most important input is our long‑range plan (LRP). It models multiple years and aligns to long‑range strategic outcomes.

When we cycle into the annual budgeting process, the LRP is our starting point. It provides us with a guidance point of  where we need to land. 

Q: How do you structure revenue planning for new products or regions where you have no historical data?

RK: When scaling to new, untested areas, you always look at the data you do have. We look at comparable market launches where we deployed people on the ground, and for new products, we use prior rollouts in existing markets as a proxy.

Yes, every market is unique, but we use these historicals as a starting point and model prudently for smaller product lines. We continue to monitor our metrics with each product launch. Our management reporting dashboards are live and we can monitor client take up and volumes almost immediately. In addition, we have a quarterly forecasting cycle, so we can adjust things very quickly and pivot where necessary

Q: How do you include big brand spend marketing campaigns into your budget,  like Airwallex recently did with McLaren and Arsenal?

RK: We’re really excited about our partnerships with McLaren and Arsenal. Brand investments don’t immediately translate into financial results, which makes it doubly important to look at other metrics and monitor them over time to see the impact.

At the start of these investment decisions it's always possible to look at the spend on brand marketing as part of the total marketing budget or in relation to revenue. When the brand campaign is live, it’s important for the finance team to stay close to campaign performance – i.e. initial branded search volumes and unique site visits, which over time convert into inbound traffic and new customers. 

Q: What's your philosophy on "cost of growth," especially for long-term bets that won't pay off for years?

RK: This is where finance becomes a true growth enabler. Our philosophy is built on understanding the lead time or cycle time of investments.

If you want growth in new regions three years from now, you have to make the investments today. A good example is securing a new market licence: There’s a significant build phase across advisory, compliance, and hiring before the first revenue. As an example, in 2024 we applied for a licence in Brazil, which we obtained in 2025 and which will add to our growth numbers as of next year.

Finance's job is to help the business model that full investment cycle – what it takes, how it ramps and when returns are realistic – so we’re making deliberate bets with a clear payback logic, even if returns are multi‑year. It's important to invest early to enable topline growth in 2 or 3 year’s time.

Q: How do you make budget ownership real for functional leaders, especially in non-revenue departments?

RK: It's different for each department. For Sales, it's straightforward. You can monitor spend against clear productivity and growth metrics.

For cost centres like Legal or Finance, budget discipline is the focus. We hold leaders accountable for how much they spend and where. We’re not defining their project‑level OKRs – that’s their remit. We’re ensuring they execute within the boundaries of the spend they were approved for.

Q: What does your finance tech stack look like during budgeting, and where does the Airwallex product fit in?

RK: We run core budgeting and modeling in our ERP/FP&A stack. Where Airwallex becomes critical is in operationalising the plan we just approved.

If we decide to open a new entity in a new market, we can quickly set up an account, connect to our ERP and procurement systems via API, enable spend controls, and get moving fast. In contexts where traditional setups can take months, speed‑to‑market matters. Having global entities on one platform – with consistent APIs, reporting, and visibility – is the real value driver.

We also control vendor and subscription spend by issuing vendor‑specific virtual cards with preset limits. If a tool is sunset, we freeze that card and the spend stops immediately. That level of granularity prevents “zombie” licences and keeps budgets honest.

For multi‑entity operations, centrally managed approval policies and unified visibility help Finance act mid‑quarter – without waiting on slower reconciliation cycles – so variance detection leads quickly to action.

For ongoing actuals to budget reviews, we utilise our FP&A tool to allow business to self-serve and drill down to monitor spend versus budgets.

Q: Once the budget is set, how do you manage it "in-season" to avoid surprises?

RK: We operate on a quarterly cycle. This allows us to be agile and pivot quickly. If we see in Q1 that a new product is ramping faster than budgeted, we can adjust and allocate more for the next quarter. If we outperform the top line and find pockets of opportunities, we could immediately double down on the marketing budget. A short cycle rhythm allows us to act throughout the year rather than waiting for the next year’s budget.

Tactically, we run a set of monthly financial reviews and quarterly business reviews, and we watch a small set of leading indicators weekly – pipeline quality and conversion pacing, capacity throughput in onboarding/support/risk, hiring vs. enablement productivity, and large vendor commitment drift. Clear thresholds and owners help turn signals into action quickly.

Q: What's your parting advice for finance leaders at other high-growth companies?

RK: Always understand what metrics your organisation is optimising for at its current stage. The focus changes.

In the beginning, it’s often about top‑line growth. Then cash discipline becomes more important. After that, profitability takes centre stage. Your budgeting process – and the trade‑offs you make – must reflect the metric which matters the most right now.