You have done what most financial advisors consider the gold standard of retirement saving: you have maxed out both your 401k and your Roth IRA. But now you are staring at extra cash in your bank account and wondering what to invest in after maxing 401k and Roth IRA. The good news is that you are already ahead of roughly 90 percent of American workers. The even better news is that a clear, strategic priority waterfall exists for every dollar beyond those retirement accounts. This guide will walk you through exactly where to deploy that surplus capital, adjusted for your income level, tax situation, and financial goals, so that no dollar sits idle earning next to nothing in a savings account.
Key Takeaway
After maxing out your 401k and Roth IRA, the optimal next steps typically follow this priority order: mega backdoor Roth (if available), HSA contributions, I-bonds for inflation protection, a taxable brokerage account with tax-loss harvesting, 529 plans for education goals, and finally alternative investments like real estate crowdfunding. The right sequence depends on your income level, tax bracket, and specific financial goals.
Why You Need a Priority Waterfall for What to Invest in After Maxing 401k and Roth IRA
A priority waterfall is a decision-making framework that ranks your next investment options from highest to lowest expected after-tax value. Without one, you risk parking money in a generic savings account earning 4 to 5 percent (before taxes and inflation erosion) when you could be compounding it far more efficiently elsewhere.
The concept is simple: each dollar you earn after covering essentials and maxing retirement accounts should flow down a sequential list of investment vehicles, stopping at the highest-priority option that you have not yet filled. Once that bucket is full or unavailable to you, the dollar moves to the next tier.
Here is the general priority waterfall, which we will break down in detail throughout the rest of this article:
- Mega Backdoor Roth — up to $46,000 additional in Roth savings (2024 figures)
- Health Savings Account (HSA) — the only triple-tax-advantaged account available
- I-Bonds — inflation-protected, tax-deferred savings bonds
- Taxable Brokerage Account — with a disciplined tax-loss harvesting strategy
- 529 Education Savings Plans — if you have children or education goals
- Real Estate Crowdfunding and Alternatives — for diversification beyond stocks and bonds
Let us now explore each tier in depth so you understand exactly where to invest after retirement accounts are maxed.
Tier 1: The Mega Backdoor Roth — Your First Stop After Maxing Retirement Accounts
If your employer offers this option, the mega backdoor Roth is widely considered the single best move for investors wondering what to invest in after maxing 401k and Roth IRA. It allows you to contribute after-tax dollars to your 401k above the standard $23,500 employee limit (2025) and then convert those dollars into a Roth account, where they grow and can be withdrawn completely tax-free.
How the Mega Backdoor Roth Works
The total 401k contribution limit for 2025, including employer contributions, is $70,000 for workers under 50 and $77,500 for those 50 and older. Most people only use the employee deferral portion ($23,500). The mega backdoor Roth lets you fill the gap between what you and your employer have contributed and that $70,000 ceiling with after-tax contributions, which are then converted to Roth.
For example, if you contribute $23,500 and your employer matches $7,000, you have used $30,500 of the $70,000 limit. That leaves $39,500 you could potentially contribute as after-tax dollars and convert to Roth.
The mega backdoor Roth is the closest thing to a financial cheat code that exists in the tax code. It effectively triples or quadruples the amount of money you can shelter in a Roth account each year, and yet fewer than 20 percent of 401k plans currently allow it.
Who Qualifies
Not everyone can use this strategy. Your employer plan must allow after-tax contributions (separate from Roth 401k deferrals) and must permit either in-plan Roth conversions or in-service withdrawals. Check with your plan administrator or HR department. If your plan does not support this feature, skip to Tier 2.
Income-Based Consideration
This strategy is particularly powerful for high-income earners in the 32 percent federal tax bracket and above (single filers earning over $191,950 in 2024) because it provides a massive Roth conversion opportunity that is otherwise unavailable through traditional Roth IRA contributions, which phase out at $161,000 for single filers.
Tier 2: HSA Contributions — The Triple Tax Advantage Most People Overlook
If you are enrolled in a high-deductible health plan (HDHP), the Health Savings Account deserves serious attention. It is the only account in the United States tax code that offers a triple tax benefit: contributions are tax-deductible, growth is tax-free, and withdrawals for qualified medical expenses are tax-free.
For 2025, contribution limits are $4,300 for individuals and $8,550 for families, with an additional $1,000 catch-up for those 55 and older. While these limits are modest compared to a 401k, the HSA functions as a stealth retirement account when used strategically.
The advanced strategy is to pay current medical expenses out of pocket, save your receipts, and let your HSA investments grow for decades. You can reimburse yourself for those expenses at any time in the future, even 20 or 30 years later, effectively creating a tax-free withdrawal mechanism with no time limit.
Tier 3: I-Bonds and the Taxable Brokerage Account Strategy After 401k
I-Bonds: Inflation-Protected Foundation
Series I Savings Bonds, issued by the U.S. Treasury, offer a guaranteed way to keep pace with inflation. Each individual can purchase up to $10,000 per year electronically through TreasuryDirect.gov, plus an additional $5,000 in paper bonds through tax refunds.
I-bond interest is composed of a fixed rate (currently 1.20 percent as of the latest reset) plus a variable rate tied to the Consumer Price Index. The interest is exempt from state and local taxes, and federal tax can be deferred until redemption. For investors in high-tax states like California or New York, this state tax exemption adds meaningful value.
I-bonds work best as a complement to your emergency fund or as the conservative allocation within your broader portfolio. They are not a growth vehicle, but they are one of the safest places to park money while maintaining purchasing power.
Taxable Brokerage Account Strategy After 401k: Your Flexible Wealth Builder
For most investors, a taxable brokerage account strategy after 401k will become the primary vehicle for building wealth beyond retirement accounts. Unlike 401k and IRA accounts, a taxable brokerage account has no contribution limits, no income restrictions, and no early withdrawal penalties. The trade-off is that you owe taxes on dividends, interest, and capital gains each year.
However, with the right strategy, you can minimize this tax drag significantly:
- Tax-loss harvesting: Systematically sell positions at a loss to offset capital gains elsewhere in your portfolio. Losses exceeding gains can offset up to $3,000 of ordinary income annually, with unlimited carryforward. Automated platforms like Betterment and Wealthfront estimate this adds 0.5 to 1.5 percent in annual after-tax returns.
- Asset location optimization: Hold tax-inefficient assets (bonds, REITs, actively managed funds) in your tax-advantaged accounts and keep tax-efficient holdings (broad index funds, growth stocks, municipal bonds) in your taxable account.
- Long-term capital gains rates: Hold investments for more than one year to qualify for the 0, 15, or 20 percent long-term capital gains rate instead of ordinary income tax rates that can reach 37 percent.
- Tax-efficient index funds: Choose funds with low turnover ratios. Total market index funds from Vanguard, Fidelity, or Schwab typically distribute minimal capital gains because of their passive strategy and, in Vanguard is case, the patented ETF share class structure.
- Direct indexing: For portfolios above $100,000, consider direct indexing, which involves buying individual stocks that make up an index rather than the fund itself. This unlocks hundreds of individual tax-loss harvesting opportunities each year.
Comparing the Best Investments After Maxing Retirement Accounts: A Side-by-Side Analysis
To help you evaluate where to invest after retirement accounts are maxed, here is a detailed comparison of each option based on key factors that matter most to post-retirement-account investors:
| Investment Vehicle | Annual Contribution Limit | Tax Treatment | Liquidity | Expected Annual Return | Best For |
|---|---|---|---|---|---|
| Mega Backdoor Roth | Up to $46,500 (varies by plan) | Tax-free growth and withdrawals | Low (retirement account rules apply) | 7 to 10 percent (market-dependent) | High earners with qualifying plans |
| HSA | $4,300 individual / $8,550 family | Triple tax-free | Medium (tax-free for medical expenses) | 7 to 10 percent (if invested in equities) | Anyone with an HDHP |
| I-Bonds | $10,000 electronic + $5,000 paper | Tax-deferred, state tax-exempt | Low (1-year lockup, 3-month interest penalty if under 5 years) | 3 to 5 percent (inflation-adjusted) | Conservative savers, emergency fund supplement |
| Taxable Brokerage | Unlimited | Taxable (favorable long-term capital gains rates) | High (sell any time) | 7 to 10 percent (market-dependent) | Everyone — the universal overflow account |
| 529 Plan | No federal limit (gift tax applies above $18,000/year) | Tax-free for qualified education expenses | Low (10% penalty for non-education use) | 5 to 8 percent (age-based portfolios) | Parents and grandparents saving for education |
| Real Estate Crowdfunding | Varies by platform | Taxable (may include depreciation benefits) | Very low (3 to 10 year lockups common) | 8 to 12 percent (projected, not guaranteed) | Investors seeking diversification beyond stocks |
These numbers make it clear that no single vehicle is universally superior. The best investments after maxing retirement accounts depend on your specific tax bracket, time horizon, and whether you need liquidity or can afford to lock up capital for extended periods.
Tier 4: 529 Plans — Education Savings with Powerful Tax Benefits
If you have children or plan to, a 529 plan should be on your radar. Contributions grow tax-free, and withdrawals for qualified education expenses — including tuition, room and board, books, and up to $10,000 per year for K-12 tuition — are also tax-free at the federal level. Many states offer an additional state income tax deduction for contributions.
In 2024, a significant new rule took effect under SECURE Act 2.0: unused 529 funds can now be rolled over into a Roth IRA for the beneficiary, subject to a $35,000 lifetime limit and annual Roth IRA contribution limits. This dramatically reduces the risk of overfunding a 529 plan, which was previously a major deterrent.
For high-income families, 529 plans also offer estate planning benefits. You can superfund a 529 plan with up to five years of gifts at once — $90,000 per beneficiary in 2024 ($180,000 for married couples) — without triggering gift tax, effectively removing that money from your taxable estate while maintaining the ability to change the beneficiary.
Tier 5: Real Estate Crowdfunding and Alternative Investments
For investors who have addressed the first four tiers and still have capital to deploy, real estate crowdfunding and alternative investments offer meaningful portfolio diversification. Platforms like Fundrise, CrowdStreet, and RealtyMogul allow you to invest in commercial and residential real estate projects with minimums ranging from $10 to $25,000.
The appeal of real estate crowdfunding lies in its low correlation with the stock market. During periods of equity volatility, real estate income streams can provide portfolio stability. Many platforms target annual returns of 8 to 12 percent through a combination of rental income and property appreciation, though these returns are projected and not guaranteed.
Important Considerations
- Liquidity risk: Most real estate crowdfunding investments have lockup periods of 3 to 10 years. Do not invest money you may need in the near term.
- Tax treatment: Income from real estate crowdfunding is typically taxed as ordinary income, though depreciation pass-throughs can offset some of this tax liability.
- Platform risk: Unlike a brokerage account holding index funds, your investment is tied to a specific platform and its ability to manage properties effectively.
- Accreditation requirements: Some platforms and deals are limited to accredited investors (net worth over $1 million excluding primary residence, or income over $200,000 for single filers).
The Decision Flowchart: Adjusting Your Strategy by Income and Goals
Your specific situation should dictate how you move through the priority waterfall. Here is how to think about it based on your income level and primary financial goals