An AI Skill for Our (Original) Apartment Acquisition Model
I’ve been working on a project to make our library of Excel models AI-ready. The idea is straightforward — pair every A.CRE Excel model with an AI Skill, a packaged set of instructions and reference files that teaches an AI assistant how to operate that specific model on your behalf. The Apartment Acquisition Model is another in the library now AI-ready, and this post introduces the AI Skill we built to accompany it.
Think of this as a sister post to the Multifamily (Apartment) Acquisition Model post, which walks through the model itself — sections, inputs, outputs, and mechanics. If you haven’t seen that one yet, start there. This post focuses specifically on the AI Skill: what it does, how it works, and how to use it.
- While we refer to these as Claude Skills (or AI Skills, Agent Skills), the instructions inside the Skill are largely platform-neutral. You can use the Skill with Claude in other platforms such as ChatGPT, Gemini, or any other capable AI assistant. You can also use these in Claude in Excel, ChatGPT in Excel, etc.
What is an AI Skill?
If you’re new to the concept, an AI Skill is a packaged set of instructions and reference files that an AI assistant loads alongside your file. It teaches the assistant things it wouldn’t otherwise know — in this case, every input cell, every output, the four user roles the Apartment Acquisition Model serves, the modeling discipline behind apartment underwriting, and the most common ways analysts get the cash flow and waterfall math wrong.
The result is an AI assistant that can actually operate the model on your behalf, rather than one that talks about apartment underwriting in the abstract.
For a primer with a short video tutorial, see our practical guide to Claude Skills.
What the AI Skill Does for You
An apartment acquisition is one of those deals where the analyst’s role completely changes which numbers matter. The acquisitions analyst cares about price, leverage, and unlevered/levered returns. The sponsor structuring a partnership cares about the waterfall split and the promote. The LP cares about what they actually earn after the sponsor’s promote and fees. The model serves all of these — but feed an analyst the wrong outputs for their role, and the analysis ends up worse, not better.
So the Skill handles a few jobs for you that you’d otherwise be doing manually.
Role Triage
The Skill opens by asking which side of the deal you’re on, then tailors everything downstream to that role:
- Acquisitions analyst / sponsor — underwriting a property to bid on. Price, leverage, unlevered and levered returns.
- Sponsor structuring a JV / syndication — sizing the LP/sponsor partnership and modeling the waterfall.
- LP / capital allocator — re-underwriting a sponsor’s deal under your own assumptions.
- Student / Accelerator member — learning how the model works.
Populating Inputs Conversationally
You can paste in a T-12 summary, upload a rent roll, or attach an offering memorandum — the Skill pulls the relevant terms (in-place vs. market rent by unit type, operating expense line items, purchase price method, loan sizing assumptions, and waterfall hurdles) and stages them for the model. Nothing writes to the workbook until you confirm.
Catching Common Mistakes
The Skill is built around the actual mistakes analysts make on this model. A few it catches automatically: incomplete rent roll rows that silently corrupt the SUMIF aggregation across every monthly engine; Cap Rate Growth entered as 0.25 when the input expects basis points (so 25); In-Place rent equal to Market rent on a deal you’ve described as value-add; and Sponsor Equity set to 100%, which trips GP-only mode and zeroes out every LP output. None of these throw errors — they all produce silently wrong answers, and the Skill flags them before you build a memo on top of them.
Framing Outputs in Your Role
The Skill tailors which outputs it surfaces first. An acquisitions analyst gets Purchase Price, Going-In Cap, Yr1 NOI, Levered IRR, Equity Multiple, Avg Cash-on-Cash, Min DSCR, and Initial Equity — framed around “at this price and leverage, here’s what your equity earns and what the lender will tolerate.” A sponsor structuring a partnership gets LP IRR/EM, Sponsor IRR/EM, and the full distribution split — plus a pedagogy note the first time waterfall outputs appear about how this model uses partnership-paid promote, which shifts outputs hundreds of basis points relative to the LP-paid promote convention some sponsors expect. An LP gets their own re-underwrite plus a brief sensitivity comparing their assumptions to the sponsor’s case on the two or three inputs that move returns most.
Operating Contexts (Chat / Cowork and Claude in Excel)
The Skill works in two environments. You can upload the Excel file to a Claude conversation and have Claude operate the model via code execution — or use Claude in Excel and operate the model live with Claude reading and writing to the workbook directly. The Skill handles both, with the mechanics adjusted under the hood. And as noted earlier, the Skill is also portable to other AI assistants, though the integration may be lighter.
A Note on the Underlying Model
The Apartment Acquisition Model is a 10-year (configurable up to 15) DCF-based pro forma for stabilized or value-add multifamily acquisitions. It handles up to 34 unit types, an in-place vs. market rent value-add module, a fixed-rate senior loan with optional I/O period, and a sponsor/LP equity waterfall with both IRR and equity-multiple hurdles. For the full walkthrough — sections, inputs, calculation modules, and mechanics — see the original Apartment Acquisition Model post.
Note: This AI Skill is built for v2.5 of the model. If you’ve got an older version, the Skill will flag the mismatch — but you’ll want to grab the current version of both the model and the Skill for the cleanest experience.
Video Walkthrough — Using the AI Skill
The video below walks through the full AI-assisted workflow: uploading the model, triaging your role, populating inputs from an uploaded T-12 and rent roll, and interpreting the outputs in the language of the investment decision.
Before You Use This AI Skill with the Apartment Acquisition Model
A couple of notes worth surfacing before you download.
Who this Skill is for. This Skill is built for real estate professionals with a strong grasp of financial modeling — and ideally some prior exposure to multifamily underwriting. It’s best suited to graduates of our A.CRE Accelerator real estate financial modeling program, or analysts comfortable building models from scratch. AI assistants make mistakes; the Skill assumes an analyst on the other side who can catch them. Treat its output the way you’d treat work from a sharp junior analyst — useful, fast, and always verified before it goes into a memo.
License. The Skill is distributed under the A.CRE software license, with full terms in the LICENSE.txt file included in the bundle. The short version: use it for personal, organizational, and client-facing analysis; don’t resell or redistribute it. Use by an AI assistant operating on your behalf is expressly permitted — that’s the whole point.
Download the Apartment Acquisition Model + AI Skill
To make this model accessible to everyone, it is offered on a “Pay What You’re Able” basis with no minimum (enter $0 if you’d like) or maximum (your support helps keep the content coming – typical real estate acquisition Excel models sell for $100 – $300+ per license). Just enter a price together with an email address to send the download link to, and then click ‘Continue’. If you have any questions about our “Pay What You’re Able” program or why we offer our models on this basis, please reach out to either Mike or Spencer.
Your download includes three files: the Excel model, the AI Skill (.skill file), and a short README explaining how to use them together.
We regularly update both the model and the AI Skill (see version notes). Paid contributors receive a new download link via email each time either is updated.
Frequently Asked Questions about the AI Skill for the Apartment Acquisition Model
Version Notes — AI Skill
Version 2.5
- Initial release of the AI Skill for the Apartment Acquisition Model
- Paired with v2.5 of the Excel model
- Supports both Chat / Cowork (upload the .xlsx and operate via code execution) and Claude in Excel (operate the live workbook directly)
- Includes 4-role triage, conversational input population from T-12 / rent roll / OM, and mistake-catching across rent roll integrity, value-add rent assumptions, waterfall hurdle ordering, and the GP-only equity trap
- Portable to other capable AI assistants (ChatGPT, Gemini, etc.) via the SKILL.md file
