Creating your first forecast

The forecast is the engine that drives everything else in OutBudget. The budget, the variance analysis, the analytics — they all measure how reality compares to what you planned here. Get this right and the rest follows.

A forecast in OutBudget is a set of assumptions: descriptions of what you expect to happen financially over the next one to five years. Your salary, your rent, the insurance that renews every spring, the wedding you're paying for in year two — each is an assumption with a type, an amount, and a category. The simulator runs them all forward, month by month, and draws the line.

The goal isn't precision. It's a plausible, honest picture of your financial future if today's plans hold. You'll update it as things change. Start good enough, not perfect.

The five assumption types

OutBudget models financial life across five types. Most users find everything fits within them.

Fixed — the default. Your salary, rent, phone bill. An amount that repeats every month until you stop it. Set it once; the simulator carries it forward.

One-time — a single event in a specific month. A wedding contribution, a security deposit, a flight. It appears once in the simulation and nowhere else.

Every X months — recurring but not monthly. Car insurance every six months. A quarterly gym membership. An annual professional subscription. Set the interval; OutBudget places the expense in the right months automatically.

Seasonal — only in the months you choose. Boat rental in the summer. Heating costs in the winter. Tuition during the school year. Pick the specific months that apply and the assumption stays dormant the rest of the year.

% of income — an amount that scales with what you earn. Useful when you want to spend a fixed share of your salary on discretionary spending, allocate a percentage to savings, or size a category against income rather than a hard number. The amount adjusts automatically as the underlying income changes.

The three growth types

Independently of the assumption type, you can apply a growth rule on top:

None — the assumption holds steady at its base value.

Inflation — you set a percentage and the amount compounds at that rate, so a forecast running multiple years out doesn't quietly understate itself.

Absolute — you set a fixed monetary increase per year. Useful for any line that grows by a number rather than a rate.

This matters most for projections beyond a year, where a flat amount would produce a forecast you already know is wrong.

Cell-level override

Any single month can be overridden without changing the underlying assumption. December always has higher gift spending. A one-off bonus lands in March. A particular quarter runs hot. Edit the specific cell; the rest of the assumption stays exactly as it was.

Income: what to model

Start with what you're confident about.

Your base salary is a fixed monthly assumption in the currency it arrives in. A year-end bonus is a one-time assumption in the month it lands. Stock vesting on a regular schedule fits the every-X-months type. For variable or freelance income, use your realistic floor rather than your optimistic ceiling — conservative assumptions make for useful variance, not false confidence.

Growing income belongs in the growth type. If a side project currently earns €500/month and you expect 10% year-on-year growth, model it that way and see what the curve looks like at 24 or 36 months.

Expenses: how granular to go

Too many assumptions becomes a maintenance burden. Too few and variance loses meaning.

A practical middle ground: one assumption per meaningful recurring line, then a single catch-all for everything else. Meaningful lines typically include rent or mortgage, utilities, insurance, subscriptions, loan repayments, groceries (monthly average), travel (quarterly or annual), and any regular commitments.

The one-offs matter most. The €15,000 wedding contribution in March of next year. The move deposit. The laptop replacement. These don't recur, but they create significant dips in the projection if you don't account for them. Enter them as one-time assumptions in the right months.

Why model five years, not just one

The one-year view tells you whether your finances work. The five-year view tells you where they're going.

A rent increase that seems manageable this year compresses your savings rate materially by year three. Side income growing at 10% per year changes the picture completely by year four. A one-off expense in year two shifts the trajectory in ways that only appear when you see the full runway ahead.

You don't have to nail the five-year view from day one. Start with 12 months of solid assumptions, review the metrics, and extend once the near term is realistic.

Reading the key metrics (KPIs)

Once your assumptions are in, the forecast surfaces five numbers worth focusing on. Each one answers a different question about the plan you've just built.

Net cash flow — the total of money in minus money out across the forecast window. A positive number means the plan accumulates over the period; a negative number means you're drawing down. Neither is wrong in isolation, but you should know which it is and why.

Monthly average — net cash flow divided by the number of months in the window. Useful as a sense-check: does this match the monthly rhythm you have in your head? If the number feels too high or too low, an assumption is probably off.

End balance — where your total balance lands at the end of the forecast window, after every assumption has played out. This is the headline number for any multi-year plan: the answer to "if I follow this, where do I end up?"

Negative cash flow — the count of months in which more money goes out than comes in. Some of these are expected (the wedding, the annual insurance, a planned large purchase). Others may signal an assumption that doesn't reflect reality. Either way, it's better to see them now than when they arrive.

Negative cumulative — the count of months in which your running balance dips below zero. This is the one to watch most carefully: even a single month here means the plan, as written, has you running out of money at some point. Zero is the target.

For a deeper look — category breakdowns, balance trajectories over time, and the rest — see the Analytics section.

Step-by-step

1. Add your income

Go to Forecast → Add assumption and add your primary income as a fixed monthly assumption. Add bonuses, vesting, and secondary income sources with the appropriate types.

2. Add fixed expenses

Add recurring commitments: rent, utilities, subscriptions, loan repayments. Use fixed for monthly items, every-X-months for anything on a different cycle.

3. Add growth and variable items

Apply growth rates to assumptions you expect to change over time. Add a catch-all variable spending assumption at a realistic monthly average.

4. Add one-offs

Think through the next 24 months for known events. Add each as a one-time assumption in the month it's expected: travel, deposits, planned purchases, contributions.

5. Review the KPIs

Check the five headline numbers. Is net cash flow pointing the right direction? Does the monthly average match your intuition? Where does end balance land? Are there negative cash flow months you didn't expect — and crucially, is negative cumulative at zero? If any number looks off, an assumption is probably off. Adjust until the picture reflects what you actually expect and what you are aiming for.

Common questions

How do I model income that varies a lot month to month? Use a conservative monthly average as your fixed assumption. For months you know will be higher — a commission quarter, a seasonal spike — add a supplemental one-time assumption. This gives you a floor to plan from and makes the upside visible without baking optimism into the baseline.

My income is in USD and my rent is in EUR. Does the forecast handle that? Yes. Each assumption is in its own currency. The simulator converts everything to your base currency using the rates you've set, so the chart shows a single consolidated view. When you update an FX rate, the projection updates automatically.

How often should I update the forecast? When something material changes: a new salary, a cancelled subscription, a plan that shifted. You don't need to touch it monthly — the forecast should reflect what you actually expect, not an audit of every small adjustment. Significant changes to income or major expenses warrant an update; minor drift is what variance is for.