17/08/2026
1. Gridlines off before you type a single cell of an investment banking model.
Two seconds of work, and it is the first thing I notice when a file lands. Leaving them on tells everyone this is your first build.
2. Colour every cell by where the number came from.
Blue for a hardcode, grey fill for an assumption someone is meant to change, green for a link to another tab, purple for a data provider pull, black for formulas and labels. A reviewer then knows where your assumptions live without opening a single cell.
3. Never bury a hardcode inside a formula.
=D14*1.029 is invisible. Nobody finds it, nobody flexes it, and it survives all the way into the version that goes out. Put the number in an assumption cell and point at it.
4. Same period, same column, on every tab.
The moment column E means 2026 on one tab and 2027 on another, every cross-tab link becomes a guess. One start year on the Control tab, driving every header in the file.
5. Build the check rows before you need them.
Balance sheet and cash, sitting where you can see them. That is how you know in one glance that the model still holds after the change you just made at 1am.
None of this makes your numbers right. It makes them checkable, and that is what gets you staffed again.
Comment "SETUP" and I'll send you the setup steps, the full colour legend and the walkthrough of my Nestlé / Danone model, tab by tab.
Welcome to Nico Schwarz. I'm a former large cap M&A banker in Zurich who now teaches IB Prep at HSG & Bocconi and helps students break into investment banking across Europe via NeverBanked.