Tax-Loss Harvesting Software: What to Check Before You Buy

Updated September 26, 2026.

Choose tax-loss harvesting software by the work you need it to perform: organizing records, supporting a tax decision, or implementing a managed strategy. A connected dashboard, an AI advisor and an automated investment manager are different purchases. None should be judged by a promised amount of tax savings.

The most useful tool is one whose inputs and responsibilities you can explain. Before comparing prices, identify who verifies the tax lots, checks outside activity, decides whether a sale makes sense, places trades and prepares the return. This guide focuses on that buying decision; the cross-account wash-sale guide covers the records review itself.

Start with the service you actually need

A household may use more than one category. Paying for advice does not necessarily replace brokerage records or tax preparation. Likewise, using a managed portfolio does not eliminate the need to coordinate transactions at other institutions.

The six capabilities worth testing

1. Tax-lot detail you can reconcile

Ask to see acquisition dates, quantities, adjusted basis and the account associated with a candidate loss. Compare one ordinary position and one transferred position with the brokerage records. A total unrealized gain or loss is useful for orientation, but it does not tell you which lot an order will sell.

The acceptance test is straightforward: can you trace the proposed amount to records you recognize? If transferred basis is missing, the tool should expose that gap rather than fill it with an unexplained assumption.

2. Clear account coverage

Make a list of relevant individual, joint and retirement accounts, plus household activity that may matter. Then mark each account as connected with adequate detail, connected with limited detail, or outside the tool.

Account count alone is a weak measure. Ten connected balances with no transaction history may be less useful for this task than a smaller set of complete records. Ask whether a successful connection means holdings only, transactions, tax lots, or some combination.

3. A wash-sale explanation, not just a badge

The tax review concerns substantially identical purchases in the 30 days before or after a loss sale. Activity in other accounts can matter. An application should make its scope visible: the dates reviewed, securities considered, missing information and whether the result is a calculation or a prompt for further investigation. IRS Publication 550

Do not accept “wash-sale safe” as a substitute for an explanation. If a provider cannot describe the limits of its check, you cannot determine whether those limits fit your household.

4. Investment consequences alongside tax estimates

A candidate should lead to questions about allocation, exposure, transaction costs and any time out of the market. A tax decision that creates an unwanted investment position is not automatically an improvement.

Ask whether the analysis considers your reason for owning the position. A short-term liquidity need and a decades-long allocation may call for different discussions, even when the displayed loss is the same.

5. Explicit execution responsibility

Does the service merely show an opportunity, recommend a course, or place authorized trades? Which agreement grants that authority? Where are confirmations recorded? Can you see the lot instructions and the accounts affected?

For a self-directed tool, a clear boundary is a strength: you know what remains yours to implement. For a managed service, evaluate the actual mandate and account eligibility rather than assuming every outside account is managed too.

6. Records that survive the dashboard

Before subscribing, check whether you can retain the evidence needed for later review: transaction confirmations, relevant data dates, assumptions and any calculations. Ask what happens to access if you cancel.

A polished answer that cannot be reconciled months later is a poor foundation for tax reporting. Your tax preparer needs the actual records, not a screenshot of a projected benefit.

Where Mezzi fits

Mezzi supports a connected financial picture and AI guidance. Supported investments can sit alongside banking, liabilities and manually entered assets; AI Personalization adds goals and preferences. This can help put a tax-related question in context—for example, whether available cash and a near-term goal change what you need to investigate. Mezzi account groups

Its role should not be overstated. Account connections do not guarantee complete tax lots or every relevant household transaction, and Mezzi does not execute trades simply because an opportunity is discussed. The user remains responsible for implementation and for obtaining appropriate tax review.

Mezzi offers a free entry point, with Advisory at $399 annually and Concierge at $999 annually. Compare the plan's broader advice and support features with your needs; do not buy it on an assumption that it will produce a particular annual tax saving. Mezzi pricing

When managed investing belongs on the shortlist

Betterment provides automated investing with eligible taxable-account tax-loss harvesting. Its standard automated-investing price is $5 monthly, switching to 0.25% annually at $24,000 in qualifying balances or at least $200 in qualifying recurring monthly deposits; fund expenses are additional. Premium has separate fees and eligibility. This buys ongoing managed implementation, a different responsibility from self-directed analysis. Betterment pricing

Its tax-loss harvesting disclosure explains that even linked external accounts can create wash-sale conflicts the service cannot prevent. Establish the relevant account and household setup before assuming that managed harvesting covers every investment you own.

Evaluate the portfolio you would hold, any transition from current assets, management and fund costs, and how outside activity must be coordinated. A lower subscription price is not equivalent savings if you would also be taking over work you currently delegate.

This is a category comparison based on official documentation, not a matched trial of tax outcomes. We do not rank providers by claimed tax alpha because outcomes depend on investor circumstances and methodology.

Require a result you can audit, including a reason to do nothing

A useful software demonstration should show more than a ranked list of losses. Use fictional inputs with a known missing field: one losing position has verified basis, another has no basis record, and a third has recent related account activity requiring review.

The tool should not rank all three as equally actionable. It should distinguish a candidate, an incomplete calculation and a transaction requiring additional checks. Ask where those statuses appear and whether the software actually executes trades or only supplies analysis.

This is a proposed acceptance test, not a report of observed product performance. Apply it to Mezzi and any specialist candidate. If the selected service lacks the records or functionality needed for your intended workflow, a polished explanation is not enough to close the gap.

A 20-minute evaluation exercise

Use one position you understand and your own institution records. Ask the prospective tool to identify what it knows and what it does not. Then complete this checklist:

• Can I reconcile the basis, quantity and data date?
• Are missing accounts and transactions identified?
• Does the explanation distinguish a potential loss from a tax saving?
• Does it discuss investment tradeoffs and uncertainty?
• Is execution responsibility explicit?
• Can I retain enough evidence for later review?

A failure is useful information. You may need a different data source, a narrower use for the tool, or a professional engagement. The objective is a dependable process, not the highest number of opportunities on a screen.

Frequently asked questions

What is the best tax-loss harvesting software?

The right choice depends on whether you need records, financial guidance, managed execution or tax reporting. Compare actual data coverage and responsibility before ranking products by price.

Does Mezzi execute tax-loss harvesting trades?

Mezzi supports financial guidance. Connecting accounts does not authorize it to sell securities. Implementation remains with you and your institution or a separately authorized manager.

Can software guarantee tax savings?

No. The result depends on usable losses, applicable rules, gains, future transactions, costs and the investor’s tax circumstances. A displayed loss is not the same as a tax saving.

What should I test before paying?

Reconcile a known position with institution records, identify missing household activity, inspect assumptions, establish execution responsibility, and verify that useful records can be retained.