The open student Q&A inside BudgetDog Academy Q&A consistently produces questions that go well beyond basic budgeting. This week’s session was no exception. Self-employed students, business owners, and investors brought advanced retirement and tax questions that required real, specific answers.
Here is what came up — and what you need to know if any of these situations apply to you.
What Is the Mega Backdoor Roth and Who Can Use It?
The mega backdoor Roth is one of the most powerful retirement savings strategies available — and most people have never heard of it.
Here is how it works:
1. You contribute after-tax dollars to your 401k beyond the standard pre-tax or Roth contribution limit.
2. Your plan must allow after-tax contributions and in-service withdrawals or in-plan Roth conversions.
3. You convert those after-tax contributions to Roth — either within the plan or by rolling them out to a Roth IRA.
The numbers for 2024:
– The total 401k contribution limit (employee + employer) is $69,000.
– The standard employee contribution limit is $23,000.
– The gap between those two figures — up to $46,000 depending on employer contributions — can potentially be filled with after-tax contributions that get converted to Roth.
The key constraint is plan eligibility. Not all 401k plans allow this strategy. Self-employed individuals using a solo 401k have more control here — they can design their plan to allow it. However, W-2 employees depend entirely on what their employer’s plan permits.
Therefore, the first step is always checking your plan documents or calling your plan administrator before assuming this option is available to you.
Solo 401k Contribution Limits for the Self-Employed
Self-employed individuals get a significant advantage with a solo 401k. They can contribute as both the employee and the employer — which dramatically increases the total amount they can shelter from taxes each year.
2024 solo 401k contribution breakdown:
-Employee contribution: Up to $23,000 (or $30,500 if age 50 or older)
-Employer contribution: Up to 25% of net self-employment income
-Combined limit: Up to $69,000 (or $76,500 with catch-up contributions)
The employer contribution is calculated based on net self-employment income after the deduction for half of self-employment tax. Getting this calculation wrong is a common mistake — and it matters, because over-contributing creates penalties.
Additionally, the deadline to establish a solo 401k is December 31 of the tax year you want contributions to count toward. Contributions themselves can be made up to the tax filing deadline, including extensions.
W-2 Versus Distribution Income for Self-Employed Students
This question connects directly to S-Corp structure. Self-employed individuals operating as S-Corps pay themselves a combination of W-2 wages and owner distributions. Those two income types are treated differently for retirement contribution purposes.
What you need to know:
– Solo 401k employee contributions must come from W-2 wages — not distributions
– Employer contributions are based on net self-employment income for sole proprietors, or W-2 wages for S-Corp owners
– Distributions from an S-Corp do not count as earned income for retirement contribution purposes
As a result, the W-2 salary you set for yourself as an S-Corp owner has a direct impact on how much you can contribute to a solo 401k. Setting that salary too low does not just create IRS audit risk — it also limits your retirement contribution capacity.
529 Plan Overages Under SECURE Act 2.0
SECURE Act 2.0 introduced a significant change for families who over-funded 529 plans: the ability to roll unused 529 funds into a Roth IRA for the beneficiary.
The key rules:
– The 529 account must have been open for at least 15 years
– Annual rollovers are subject to the Roth IRA contribution limit for that year
– Lifetime rollover maximum is $35,000 per beneficiary
– The rollover counts toward the beneficiary’s annual Roth IRA contribution limit — it does not stack on top of it
This provision removes one of the primary objections families had about over-contributing to a 529. However, the 15-year rule is significant. It means the account needs to have been established well before the beneficiary heads to college for this strategy to be available.
For families with young children and significant college savings, this makes the case for opening a 529 early — even with a small initial contribution — to start the 15-year clock.
Target Date Fund Downsides
Target date funds get recommended constantly as simple, hands-off retirement solutions. They serve a purpose — but students asked about the downsides, and there are several worth understanding.
The main limitations:
-One-size-fits-all glide path. The fund’s asset allocation shifts toward bonds as the target date approaches, regardless of your individual risk tolerance or financial situation.
-Expense ratios vary widely. Some target date funds carry higher fees than building a comparable portfolio from individual index funds.
-No tax optimization. Target date funds do not account for which accounts your assets are held in — they hold the same mix regardless of whether you are in a taxable, traditional, or Roth account.
-False sense of completion. Many investors set up a target date fund and stop engaging with their retirement strategy entirely — which means they miss opportunities to optimize as their situation changes.
Target date funds are not inherently bad. For someone who wants a default option and will not manage anything more complex, they are better than not investing. However, they are a starting point — not an optimized retirement strategy.
Portfolio Consolidation Tax Impact
Consolidating accounts spread across multiple custodians is a common goal for investors who have accumulated accounts at former employers and various brokerages. The tax impact depends heavily on account type.
The key considerations:
– Rolling over a traditional 401k to a traditional IRA: generally tax-free, no impact
– Rolling over to a Roth IRA: triggers a taxable event — the converted amount is added to ordinary income for that year
– Selling positions inside a taxable brokerage account to consolidate: triggers capital gains tax on any realized gains
The most common mistake is consolidating without mapping out the tax consequences first. A large Roth conversion in a high-income year can push you into a higher bracket or trigger additional Medicare surtax. Timing matters.
Additionally, if you are considering consolidation, evaluate whether an in-kind transfer is available — moving assets without selling them avoids triggering gains in taxable accounts.