Claude now works inside Excel as a side panel, right next to your model. Ask it in plain English what is driving your returns and which assumptions are aggressive, and it answers with a link to the exact cell. The best use is interrogating a model you did not build.
Most of us underwrite in a spreadsheet. The moment a number looks off, you are stuck scrolling through tabs trying to work out which cell drives it.
Claude for Excel sits in a side panel next to your model. You ask what is going on in plain English, and it answers with the working shown, linked to the exact cells.
The side panel you talk to, right next to your sheet. You ask questions in plain English and it reads, explains, and edits the model on your behalf.
Every tab, every formula, whether you built it or a broker sent it. Claude works across the whole workbook, not just the cell you have selected.
Every answer links back to the exact cell it came from. You see the working instead of trusting a number, so you can check it in one click.
Most investors accept the returns on a broker's sheet at face value. Now you can ask which assumptions are aggressive.
Anyone who makes real decisions off a spreadsheet model, in property or any business. The worked prompts below are written for property cash flow models, because that is what I use Claude for, but every one transfers to any Excel model you rely on.
You install it once. After that, Claude opens in a side panel in any workbook you have open, ready to read the model in front of you.
Get Add-ins or Add-ins) and search Claude by Anthropic for Excel. Click Add.Ctrl+Alt+C on Windows, Ctrl+Option+C on Mac.You need Microsoft Excel with a Microsoft 365 account, on desktop or the web, and a paid Claude plan, from twenty dollars a month on Pro. Claude can edit your model, so work on a copy for anything important and check its changes before you rely on them. It reads and edits through the side panel, so there is nothing new to learn in your formulas. Menu labels shift between Excel versions, so if a name does not match exactly, look for the nearest equivalent under Insert or Home.
Open your model, open the Claude panel, and paste any of these. Edit the brackets to match your sheet first, so the labels line up with your own tabs and figures.
Each one asks Claude to show its working and cite the cells, so you can check every answer rather than take it on trust.
Walk me through what is driving the [IRR, net yield, or cash-on-cash return] in this model. List the three or four assumptions that move it the most, and for each one cite the exact cell it lives in. Do not change anything yet. I just want to understand what this return depends on before I trust it.
Rerun this model with a tougher set of assumptions: - rent growth at [2]% instead of [5]% - a [3] month void every [2] years - interest at [6]% Show me the new [IRR and yearly cash flow], and tell me which year, if any, turns negative. Keep all my existing formulas intact, and cite the cells you changed.
Go through every assumption in this model and flag which ones look optimistic against normal market ranges. For each one, show me: - the cell - the current value - a more conservative figure you would use instead I want to know where this model is flattering the deal, and by how much.
Find the break-even points in this model. At what [rent], [occupancy], and [exit yield] does this deal stop making money? Change one variable at a time, hold the rest as they are, and tell me the tipping point for each. Cite the cells you tested so I can see the range I am working with.
I have two models here, in [these two tabs, or these two files]. Compare them side by side on [net yield], [IRR], [total cash in], and [payback period]. Tell me which is the stronger risk-adjusted buy and why, and point to the exact numbers behind your answer. Flag anything that is not a like-for-like comparison.
Open your model, open the Claude panel, and paste one prompt. Claude reads the workbook, answers, and links its numbers to the cells. Check the cited cells before you act on anything. Run them in order on a new deal, or reach for the one you need on a model you already have. You do not need to write a single formula to use any of them.
Message me directly if you want to talk through a model you are looking at, or which of these prompts to run first. If property is part of your plan, I can also walk you through the opportunities I am tracking right now.
Message me on WhatsAppOne question saves you an hour of scrolling. A habit of interrogating every model means you stop buying on numbers you never actually checked.
Trace the returns, stress the downside, flag the aggressive assumptions, find the break-even, and compare two deals. Five questions that used to take an analyst an afternoon now take you a few minutes.
It works on any Excel model. I use it on property, where a single flattering assumption buried in a broker's sheet can cost you years of returns.
Every prompt in this 30-day series is one capability. FourthspaceOS bundles all of them into a single product: underwriting, comps, market research, deal sourcing, portfolio tracking, and investor reporting. The product runs natively on the same Anthropic agents and plugins you are learning to use this month.
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The setup and five prompts you just read are Day 26 of 30. The full series, daily builds, and live property workflows are on Instagram. Follow for the rest of the run.
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