Design a Caixinhas experience that helps young Brazilians build their first emergency fund.

Introduction

Caixinhas ("little boxes") are Nubank's savings pots inside NuConta. Customers can create a box for a goal, name it, add money with a tap or through automatic rules, and earn a yield linked to the CDI, Brazil's interbank rate, with daily liquidity. With around 118 million customers in Brazil, Nubank has put a savings tool in the hands of a huge share of the country's adults. Yet many young Brazilians still live paycheck to paycheck. A surprise expense such as a broken phone, a medical bill or a month without freelance income often pushes them into the credit card's revolving rate, overdraft-like products or expensive informal loans.

This question asks us to design a Caixinhas experience that helps young Brazilians build their first emergency fund. I'll clarify scope, explain why it matters for customers and for Nubank, choose a segment, map pain points, design a solution and define metrics.

Step 1

Clarify Questions (3 minutes)

• Is this an improvement to existing Caixinhas or a new product? I'll assume a new emergency-fund experience built on top of Caixinhas, so we reuse the yield, liquidity and infrastructure.

• Who are "young Brazilians"? I'll assume 18–29-year-olds who already use NuConta and the purple credit card, including students, first-job workers and gig workers.

• What does success mean for Nubank: deposits, engagement, lower credit losses, or customer financial health? I'll assume all of these matter, with the main goal being customers who can absorb a shock without defaulting.

• Any constraints? I'll assume we must keep the product simple, avoid paternalism, and comply with Central Bank rules on how investment yields are communicated.

Propose the Goal

Help young Nubank customers build an emergency fund equal to at least one month of essential expenses within a year, and use it instead of expensive credit when something goes wrong.

Define the Scope

In scope: goal setting, automatic saving, nudges, the withdrawal experience and links to credit. Out of scope: new investment products, changes to yield rates, or insurance products.