The 2% Rule: How Your Grocery Bill Becomes a Brokerage Deposit
Are you putting every dollar to work for you?
My family has been putting nearly every purchase on a credit card for years. Groceries, gas, utilities, subscriptions, the occasional dinner out. Not because I needed the credit. Because a rewards card does several things a debit card does not: it tracks every dollar I spend in one place, it returns a percentage of that spending back to me, and it comes with purchase protections, fraud liability coverage, and travel benefits that a bank account simply cannot match. Every dollar that passes through a rewards card without a destination is a dollar that does not compound.
The strategy is straightforward. Use a cash back credit card for every eligible purchase. Redirect the rewards into a brokerage account. Invest in a broad-based index fund. Repeat, every month, without thinking about it. One condition applies before anything else: if you are carrying high-interest debt, put this on hold. The interest you are paying will outpace any return the cash back generates. Clear the balance first, then come back to this.
VTI, Vanguard’s Total Stock Market exchange-traded fund (ETF), has returned an average of 8.94% annually since its inception on May 24, 2001, as of March 31, 2026, according to Vanguard fund performance data. That number is historical context, not a forecast. It spans more than two decades of market cycles, including two major crashes and a pandemic, and it is not a guarantee of what the next 20 years will produce. What it gives you is a framework for what patient, diversified investing has produced. The 2% cash back is how you put dollars into the market from spending you were already going to do. That is the leverage.
The rewards are not the story. The compounding is.
The Numbers Behind the Habit
Run a conservative scenario. A household puts $3,000 per month on a 2% cash back card. That generates $60 per month, or $720 per year, in cash back. Redirected into an index fund and left alone, that $720 per year grows to approximately $33,000 over 20 years at an assumed 8% average annual return. Double the monthly card spending to $6,000 and that figure approaches $66,000.
No extra income. No budget sacrifice. The spending was already happening. The only change is where the rewards land.
Two conditions make this work, and neither is negotiable. First, you pay the balance in full every month. The interest charge will quickly negate any investment gain: you will be moving backward while thinking you are moving forward. Second, your card spending has to mirror what you would have spent anyway. If putting purchases on a card causes you to spend more than you otherwise would, the math runs in reverse.
This strategy performs exactly as described only when both conditions hold. If you are not yet at a place where monthly spending is settled and paid, get there first.
Pick the Card That Fits Your Life
For anyone already investing through Fidelity, the answer is straightforward: the Fidelity Rewards Visa Signature Card is built for exactly this strategy. Set it up once, link it to your brokerage, and walk away. The rewards deposit automatically, the 2% rate applies to every eligible purchase, and there is no annual fee. The mechanics are simple: enable automatic monthly redemption, link it to your brokerage, individual retirement account (IRA), or 529 account, and at the end of each billing cycle your points convert to cash and deposit without any manual step. The 2% rate applies only when rewards go into a Fidelity account. Redeem for travel, merchandise, or statement credit and the value drops. You will need excellent credit to qualify.
One routing decision worth making before you set this up: if you have unused Roth IRA contribution room and your income falls below the IRS phase-out threshold, directing cash back there is the smarter default. Per the IRS, qualified withdrawals from a Roth IRA are not subject to income tax on gains. Cash back deposited into an IRA is reported as a current-year contribution and counts toward your annual limit: $7,500 for 2026, or $8,600 if you are 50 or older. Eligibility phases out for single filers earning above $153,000 and married couples above $242,000 in 2026. If those limits apply to you, or if you are already maxing your IRA, the taxable brokerage is the right destination. Consult a qualified professional before routing to a tax-advantaged account.
One caveat worth knowing: the card carries Fidelity’s name but customer service is handled entirely by Elan Financial Services, a division of U.S. Bank. If you have a dispute, a billing question, or a fraud claim, you will deal with Elan, not Fidelity. Fidelity will redirect you. The most common complaints reported across Trustpilot and Reddit involve two patterns: dispute resolution claims rejected for insufficient documentation, and payment declines when traveling internationally despite advance notification. Time spent resolving either has real cost, and that belongs in your calculus before you apply.
The card also allows rewards to be directed into accounts that belong to someone else. A spouse, a child with a custodial account, or a 529 plan are all eligible. The deposit can be split or redirected across eligible Fidelity accounts. For anyone already thinking about building wealth for the next generation, that is a meaningful feature.
Whatever card you choose, the criteria are the same: unlimited flat-rate cash back, no annual fee, and a redemption path that puts cash into a brokerage account you control.
The Lowe Down
The 2% is not the point. The habit is the point. When the reward goes to a gift card or a statement credit, it disappears into the noise of daily spending. When it goes to a brokerage account and into an index fund, it compounds. How much of your monthly spending is already going on a card that is not working for you?
Start with your must-pay expenses. Recurring charges, groceries, gas, utilities. Put them on a flat-rate 2% cash back card and make sure every dollar that leaves your account sends something back. Your budget does not change. Only where the rewards land does.
Link the card to a brokerage account and turn on automatic monthly redemption. The money moves without you.
Fidelity deposits your rewards automatically each billing cycle. When that deposit lands, buy the fund. VTI, VOO, or a comparable total market or S&P 500 index ETF. This is the one step that stays with you: a two-minute purchase, once a month. Cash sitting in a brokerage account is not investing. The finish line is the purchase, not the deposit.
Do not touch it. The account is not an emergency fund. It is a compounding position built entirely from spending you were always going to do. Let it compound with time.
It’s a no brainer.
Additional Resources
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Morgan Housel, The Psychology of Money (2020)
Disclaimer: This content is for informational and educational purposes only. It does not constitute financial, legal, or investment advice. Always consult a qualified professional. The author maintains a personal investment in VTI and VOO. Past performance is not a guarantee of future results and market conditions are subject to change.
Lowe Intelligence is a trade name of ForsythTrail LLC, a Virginia limited liability company.
I have been doing the 2% cash back for years now but always just re-applied it to the statement balance, never thought about putting it towards investments, great idea!