Build a financial plan: a step-by-step guide

The foundation: the assumptions sheet

Every good financial plan starts with an assumptions sheet. That is where all the adjustable inputs live in one place: the revenue drivers (prices, volumes, growth), the cost drivers (material ratio, salaries and headcount, fixed costs) and the financial assumptions (interest rate, payment terms, tax rate). Every other sheet calculates from this one sheet alone.

The benefit is twofold. First, it cleanly separates what is an input from what is calculated out of it. Second, you see the levers at a glance: change one assumption and the effect flows through the entire model, without you having to fix things in dozens of places.

The mechanics: three linked statements

A financial model is not a stack of separate tables but three statements that interlock. The projected P&L shows the profit, the liquidity or cash flow statement shows the real movement of money and the projected balance sheet shows the stock of assets and capital.

The flow is always the same: revenue minus costs gives the result in the P&L. That result flows, adjusted for depreciation and changes in working capital, into the cash flow. Cash flow and result change the balance sheet, that is equity, cash and debt. In the end the balance sheet has to balance: assets equal liabilities and equity. If it does not balance, there is a mistake somewhere in the model.

Getting this linkage clean and stable is the genuinely hard part, especially in Excel, where it hangs on hundreds of formulas across several sheets.

The model, without the Excel tinkering

Planvik builds exactly this model for you. You fill in guided inputs, Planvik links the P&L, cash flow and balance sheet automatically, and the balance sheet balances by construction. The result: a bank-ready Excel file in about 15 minutes.

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Principles for a clean model

Above everything else stands traceability: every reviewer, and you yourself a few weeks later, has to be able to follow every number in one step. Nested formulas like this one are the opposite of that:

=IF(B4>0,VLOOKUP(B4,Assumptions!A:F,IF(D4="A",4,5),0)*(1+B7)^E4,0)

Hardly anyone can say at a glance what this cell computes. It is better to spread the logic across several named intermediate steps until a cell reads only =BasePrice * GrowthFactor. In concrete terms, clean modeling means:

No hard-coded values inside formulas. Every number comes from a cell, ideally from the assumptions sheet. A value typed straight into a formula is invisible and gets forgotten when you update.
Consistency across rows and time. The same formula copied across a whole row, the same time axis on every sheet. A formula that changes from column to column is a source of error.
Separate input, calculation and result. Inputs go on the assumptions sheet, calculations on the working sheets, results on the overview. Never mix them.
Color coding: inputs blue, calculations black, cross-references green. This convention is familiar to anyone who works with financial models: blue may be touched, black is the result of a formula on the same sheet, and green marks a reference to another sheet, for example when the cash flow pulls a value from the P&L.
Universal terms. EBITDA, DSCR or working capital instead of made-up labels. The rows should be understandable without anyone having to ask.
One sheet per component. Overview, assumptions, P&L, cash flow, balance sheet and repayment schedule, cleanly linked to one another.
Built-in checks. A balance check (assets minus liabilities and equity must be zero) and control totals show immediately when an error has crept in somewhere.

Step by step to the finished plan

Capture the starting position. The starting point is your current situation: for an existing business the latest balance sheet with equity, assets and outstanding loans, for a startup the equity you put in. The projected balance sheet builds on that.
Gather all the assumptions. Collect on an assumptions sheet everything that steers your model: the revenue drivers (prices, volumes, growth), the cost drivers (material ratio, salaries and headcount, fixed costs) and the financial assumptions (interest rate, payment terms, tax rate). These values are later the only ones you touch.
Build up revenue. Calculate revenue bottom-up from price and volume per product, with growth and seasonality. That way every revenue figure traces back to a driver.
Plan costs and staff. Derive the variable costs from revenue, plan the staff by role including payroll costs, and set the fixed costs such as rent, marketing and IT.
Add investments and financing. Record planned purchases with their depreciation, along with the financing from equity, grants and loans including the repayment schedule.
Link the three statements. Connect the P&L, cash flow and projected balance sheet so that the result flows into the cash flow and from there into the balance sheet. Only this linkage turns individual tables into a model.
Review and iterate. Check the balance check, read off the metrics and run a base case and a worst case. Whatever looks implausible you correct at the assumption, not at the formula.

Sanity checks before you submit

The balance sheet balances: assets equal liabilities and equity, deviation zero.
The DSCR is above 1.2, so cash flow covers interest and repayment.
Liquidity never turns negative in any month.
The margins are in line with the industry, no outlier without an explanation.
A base case and a worst case show that the plan holds up even under a poorer scenario.

How to calculate the key metrics and what values are expected is covered in the guides on DSCR, the equity ratio and EBITDA.

Frequently asked questions

Excel or a tool, what should I build the plan in?

Excel gives you maximum freedom but costs time and is error-prone when it comes to linking the statements. A tool like Planvik gives you the same bank-ready model in about 15 minutes, open as an xlsx file.

Do I need accounting knowledge?

Building it by hand is easier with a basic understanding of the P&L, cash flow and balance sheet. With a guided tool your operating numbers are enough.

How long does a financial plan take?

By hand in Excel it can easily take several days; with a guided tool about 15 minutes for the first version.

How often should I update the plan?

At least once a year, and whenever an important assumption changes, such as the interest rate, prices or a larger order.