Corkscrew
AccountingA schedule built as opening balance, movements, closing balance, with each period's closing balance becoming the next period's opening balance.
Also written: corkscrew schedule, rollforward, roll forward schedule
Every rolling balance in a model takes the same shape: what you started with, what was added, what was taken away, what is left. Debt, fixed assets, retained earnings and provisions are all built this way, which is why an unfamiliar schedule in someone else's model is readable on sight.
It forces each movement onto its own line rather than letting it be absorbed into a total. The reason a balance changed becomes visible instead of something a reader has to infer by subtracting one year from the next.
It also delivers row consistency without anyone having to enforce it. Because the structure is identical in every period, one formula copies across the whole forecast, and there is nowhere convenient to type a one off exception. That matters because a typed exception inside a formula row is the error class that breaks nothing and therefore never announces itself.
The links out of a corkscrew are what tie the model together. The closing debt balance goes to the balance sheet, the movement goes to the financing section of the cash flow statement, and the balance drives the interest charge on the income statement. One schedule, three destinations.
Worked example
Debt opens at 250. Nothing is drawn and 20 is repaid, so the closing balance is 230, and 230 is the opening balance next year.
The 230 goes to the balance sheet, the 20 goes to financing on the cash flow statement, and the balance feeds interest on the income statement. Three statements served by one schedule, with every movement on its own visible line.