Why Asset “Location” Matters More Than You Think

Most investors focus on what to buy — stocks, bonds, the classic 3‑fund portfolio. But very few think about where those investments should live. And that “where” quietly affects your taxes every single year.

I’ve written before about how smart asset location can boost long‑term returns. I also compared my approach with what Google Gemini suggested for the same $1 million sample portfolio. This time, I wanted to make the whole idea more hands-on. So I built an interactive Asset Location Optimizer using Google AI Studio.

The tool takes three ETFs — VTI, VXUS, and BND — and figures out the most tax‑efficient way to spread them across a Taxable account, Roth IRA, and Traditional IRA. It reads your balances, applies your target allocation, and shows you exactly how much tax drag you’re paying today versus what you could be paying.

In the sample case, the optimized setup cuts annual tax drag from $1,674 to $585 — a savings of $1,089 per year. Let that compound for 30 years, and it adds up to $195,691 in extra wealth.

The logic behind the tool is simple:

• Bonds (BND) go in the Traditional IRA because bond interest gets taxed at ordinary income rates.

• International stocks (VXUS) go in the Taxable account to capture the Foreign Tax Credit.

• US stocks (VTI) go in the Roth IRA to maximize tax‑free growth.

• Any leftover VTI fills the remaining space.

You still end up with the same overall 48/12/40 allocation — just arranged in a smarter way.

I built the entire app using prompts (aka vibe coding) in Google AI Studio, and it turned out to be a great educational tool. It makes asset location visual and intuitive, and it shows how much taxes quietly eat into returns. It’s not a replacement for a CPA, but it’s a great way to understand the power of putting the right assets in the right accounts.

The screenshots below show the tool in action. The tool also includes an AI Chat Advisor that explains the math, tax logic, and decumulation strategies.

Disclaimer: This article is not intended to be investment advice. Consult a duly licensed professional for investment advice. The contents of this article are for educational purposes only and do not constitute financial, accounting, tax, or legal advice. Past performance is no guarantee of future results.

I Gave Three AI Tools the Same Simple Prompt. Only One Got It Right on the First Try.

In an earlier post, I explored how thoughtful asset location can improve the long‑term after‑tax return of a 3‑fund portfolio. As part of my ongoing experiments with modern AI tools, I decided to test how well they could recommend asset locations for the same sample $1 million portfolio.

The next section shows the exact prompt I used and the response generated by Google Gemini.

Prompt:

You are an experienced financial planner. I am getting ready to retire. My portfolio consists of the following accounts: Taxable $100,000, Roth IRA $50,000, Traditional IRA $850,000, Total $1,000,000. My desired asset allocation: Stocks 70% (20% of this in International stocks), Bonds 30%. I only want to use low-cost index funds and no actively managed funds. Please recommend which funds and what amounts should be placed in which account(s) i.e. taxable, Roth IRA, Traditional IRA to maximize long-term after tax return.

Response:

To maximize your long-term after-tax returns while maintaining your 70/30 asset allocation, you should prioritize asset location. This strategy involves placing less tax-efficient assets (like bonds) in tax-deferred accounts and high-growth assets (like stocks) in tax-exempt or taxable accounts. 

Asset Allocation Strategy

Based on your $1,000,000 portfolio and desired 70/30 split (with 20% of stocks in international), your target amounts are:

• Total Stocks (70%): $700,000

• U.S. Stocks (80% of stocks): $560,000

• International Stocks (20% of stocks): $140,000

• Total Bonds (30%): $300,000 

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Recommended Asset Location

Account	Amount	Asset Type	Recommended Low-Cost Fund Examples
Taxable	$100,000	International Stocks	Vanguard Total International Stock ETF (VXUS)
Roth IRA	$50,000	U.S. Stocks	Vanguard Total Stock Market ETF (VTI) or Schwab S&P 500 Index (SWPPX)
Traditional IRA	$300,000	Total Bond Market	Vanguard Total Bond Market ETF (BND) or Fidelity Long-Term Treasury Bond Index (FNBGX)
Traditional IRA	$510,000	U.S. Stocks	Vanguard Total Stock Market ETF (VTI) or Fidelity 500 Index (FXAIX)
Traditional IRA	$40,000	International Stocks	Vanguard Total International Stock ETF (VXUS)

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Strategic Rationale 

• Taxable Account (International Stocks): Placing international stocks here allows you to potentially claim the Foreign Tax Credit for taxes paid to foreign governments, which is lost if held in an IRA.

• Roth IRA (U.S. Stocks): This account provides tax-free growth. By placing U.S. stocks here—which generally have higher long-term growth potential than bonds—you maximize the value of the tax exemption.

• Traditional IRA (Bonds): Bonds generate interest income that is taxed at ordinary income rates. Holding them here defers those taxes until withdrawal, which is more efficient than paying annual taxes in a taxable account.

• Filling the Gaps: Since your Traditional IRA is your largest account ($850k), it must hold the remainder of your U.S. and International stock allocations after the Taxable and Roth accounts are filled. 

Execution Note

• Rebalancing: It is easiest to rebalance within your Traditional IRA since selling and buying assets there does not trigger immediate capital gains taxes.

• Low Costs: All recommended funds (VTI, VXUS, BND, etc.) have extremely low expense ratios (typically 0.03% to 0.08%), satisfying your requirement for low-cost index funds. 

My Observations on the Prompt and the Response

As you can see, the prompt is simple and direct. It avoids technical jargon like “asset location,” while still conveying the key details about the responder (a financial planner), the requestor (approaching retirement), and the portfolio.

The response is similarly clear and direct, and even offers strategic rationale - despite my not explicitly asking for it. Importantly, its asset location recommendation aligns with the suggestions in my earlier post (see screenshot below).

I also ran the exact same prompt through Microsoft Copilot and ChatGPT. Neither produced the correct answer on the first attempt. They did get there eventually, but only after I pointed out both logical and arithmetic errors.

Related:

Improve Long-term After-tax Return on 3-fund Portfolio using Asset Location

Disclaimer: This article is not intended to be investment advice. Consult a duly licensed professional for investment advice. The contents of this article are for educational purposes only and do not constitute financial, accounting, tax, or legal advice. Past performance is no guarantee of future results.