Investors Study Case (EN)

Sources

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Source note. All outcome metrics come from the Postmortem — Simplify Investors e2e experience (Nov 6, 2025 → Jun 30, 2026). Diagnostic data not covered by the postmortem comes from the discovery phase (La Misión, War Room Prelude, and Research Summary, n=98). Case anonymised: no broker names or internal volume figures.

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1. Context

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In one sentence. As Product Design Lead, I redesigned TaxDown's Investments section end-to-end — the most complex part of the product — starting from a counterintuitive insight: the problem wasn't the interface, it was how the data came in.

→ Investor NPS +20.4 pts YoY (40.1 → 60.5, +51%).
→ Improvement across all four segments simultaneously.
→ Goal achieved: investor satisfaction reaches the level of the rest of the user base (~60). </aside>
TaxDown is a Spanish tax filing platform that guides anyone through preparing and submitting their annual income tax return.
The Investments & Crypto section — where users declare gains and losses from stocks, dividends, funds, and crypto — is the most complex part of the entire product.
It's also the business's highest-value segment: revenue from investors with international brokers was growing +94% YoY, and crypto +74% YoY.
Investors were the fastest-growing segment and, at the same time, one of the least satisfied. Without fixing this experience, B2C growth had a ceiling.


Role	Product Design Lead — I defined the full user experience, the information architecture, and the underlying product model to make it scalable
Platform	TaxDown app (Desktop, iOS, Android, Responsive)
Team	Squad Imagineering: PM, Tech Lead, backend and frontend, with Fiscal, Operations, and Support
Timeline	Nov 2025 – Jun 2026: design, development, and 2025 tax season campaign

2. Business Problem

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In one sentence. If left unsolved, we would lose the market share we had built over four years in our highest-value segment.

→ Investor plan NPS: 33.8 vs ~61 for the overall user base.
→ Double checkouts: 50% of users with a domestic broker were forced to upgrade their plan, and 75% of those dropped off.
→ 35–40% of all support tickets came from technical errors. </aside>

Investors were growing fast but leaving unhappy — and that was slowing B2C growth. The problem had three faces:

Dissatisfaction. The investor plan NPS started at 33.8, far below the ~61 of the rest of the base. It was blocking both conversion and word-of-mouth.
Inflated plan expectations → churn. 50% of users with a domestic broker were forced to upgrade to a higher plan just to submit their broker report. Of those, 75% dropped off.
Technical errors overwhelming Operations. Broker and document failures were generating 35–40% of all support tickets.

3. User Problem

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In one sentence. Users wanted to file their investments correctly, but the system neither guided them through it nor let them understand or verify the result.

→ 0% found the investment summary sufficient.
→ Only 35.7% fully trusted their result.
→ 19% of NPS comments cited lack of guidance — which also drove 25–30% of support tickets. </aside>

The problem had three dimensions: trust, usability, and legibility.