Why Do I Owe Taxes Every Year? What High Earners Need to Know
If you just filed your taxes and wrote the IRS a check, you are not alone. Millions of Americans find themselves in this situation every April, and many simply accept it as an unavoidable part of life. But owing taxes, especially owing more than $1,000, is not just an inconvenience. It can trigger IRS underpayment penalties and interest, which means you end up paying more than just the tax itself.
The good news? This is largely a preventable problem. But here is the part most people miss: almost none of it can be fixed in April.
At SYKON Capital, we work with clients year-round on proactive tax planning, and we see the same patterns emerge again and again. Understanding where these gaps come from is the first step toward making sure you do not face the same bill next year.
What Is the IRS $1,000 Rule, and Why Does It Matter?
The IRS has what is known as the safe harbor rule. If you owe more than $1,000 after your withholding and credits are applied, you may be subject to underpayment penalties. To avoid those penalties, you generally need to meet one of three thresholds: owe less than $1,000 at the time of filing, have paid at least 90% of your current-year tax liability during the year, or have paid 100% of your prior-year tax liability (110% if your adjusted gross income exceeded $150,000).These are not just guidelines. They are the benchmarks the IRS uses to determine whether you get hit with additional charges on top of what you already owe.
Why Do High-Income W-2 Earners Owe More Than They Expect?
Most people assume that if they have a regular paycheck with taxes withheld, they should be fine. For many high earners, that assumption tends to be wrong. In our practice, we consistently see four issues that catch people off guard.RSUs and the 22% Withholding Problem
One of the most common situations we encounter is clients with restricted stock units, or RSUs, who are surprised by how much they owe at filing. When RSUs vest, your employer typically withholds at the federal supplemental wage rate of 22%. That sounds reasonable until you consider that if you are earning $300,000 or more, your effective marginal tax rate is likely well above 22%. You could be significantly underwithholding on every RSU vest throughout the year and not realize it until April. Those vested shares count as ordinary income in the year they vest, and if your withholding does not reflect your actual bracket, the gap adds up fast. We often see clients who have had multiple vest events throughout the year, each one compounding the shortfall.
The Marriage Penalty
We have this conversation often with newly married clients, and it almost always catches them off guard. The marriage tax penalty is particularly relevant for dual-income households where both spouses earn similar salaries. Your employer only knows what you make. They have no visibility into what your spouse earns. So both employers may be withholding based on income levels that look reasonable individually. But when you combine them on a joint return, your taxable income can jump into a higher bracket and your cumulative withholding may fall well short.
Worth knowing: the IRS considers you married for the entire tax year even if your wedding was on December 31st. If you recently married or became a dual-income household, this is a conversation worth having sooner rather than later.
The IRS actually built a tool into the W-4 specifically for this situation. Step 2(c) on your W-4 is designed for dual-income households and, when checked by both spouses, helps each employer withhold at a rate that better reflects your true combined tax liability. If you prefer a more conservative approach, withholding at the married filing separately rate is another option that tends to reduce the risk of coming up short. Either way, this is an adjustment that needs to happen during the year, not in April.
The Additional Medicare Tax
This one surprises a lot of the high earners we work with. If your combined household income exceeds $250,000 as a married couple filing jointly, you may owe an additional 0.9% Medicare surtax on the amount above that threshold. Here is the catch: your employer only withholds this tax once your individual wages exceed $200,000. They have no way of knowing what your spouse earns. So if you and your spouse each earn $175,000, neither employer withholds the Additional Medicare Tax, because neither of you individually crossed $200,000. But your combined $350,000 exceeds the $250,000 household threshold, and you will owe it at filing. This is a gap in employer withholding that catches many dual-income households off guard every single year, and it is one of the first things we flag when we onboard a new client who fits this profile.
Capital Gains
Capital gains are another area where we frequently see clients come in owing more than they expected. When you sell an investment at a profit, no one automatically withholds taxes on that gain for you. It is entirely your responsibility to either pay estimated taxes throughout the year or ensure you have enough additional withholding in place to cover the liability.
Short-term capital gains, on assets held less than one year, are taxed as ordinary income and can push you into a significantly higher bracket than you anticipated. Long-term capital gains are taxed at preferential rates, but for higher earners those rates can reach 20%, and the 3.8% Net Investment Income Tax may apply on top of that once household income crosses certain thresholds. When clients come to us mid-year and mention they have been actively selling positions, that is an immediate prompt for us to run the numbers and determine whether estimated tax payments are needed.
This is also why a year-end review with your advisor is so important. Before December 31st, there may still be opportunities to offset realized gains through tax loss harvesting, which involves selling positions that are sitting at a loss to reduce your overall taxable gain for the year. That window closes completely on December 31st, and we cannot go back and do it for you in April.
There is one more layer to this that we see often in our practice: coordination across accounts. Many clients have investments spread across multiple brokerage accounts, a 401(k) through work, a taxable account at one broker, perhaps an IRA somewhere else. If your advisor cannot see all of your holdings and cost basis across every account, they are working with an incomplete picture. They cannot identify which positions are sitting at a loss that could offset gains elsewhere. They cannot give you accurate guidance on whether a sale will trigger a short-term or long-term gain or even a wash sale. At SYKON Capital, one of the first things we do when working with a new client on tax planning is make sure we have full visibility into all accounts before making any recommendations. If your advisor is only seeing part of your portfolio, there is a meaningful chance that important planning opportunities are being missed.
The Fix Is Not April. It Cannot Be April.
I want to be direct about something that does not get said clearly enough: most of the solutions to an April tax bill have to happen during the tax year itself. You cannot go back and adjust your W-4 withholding for a year that has already ended. You cannot retroactively make 401(k) contributions for the prior year after December 31st. You cannot change how much was withheld from your RSU vests six months ago. You cannot harvest losses on positions you should have sold in November. By the time you are sitting across from your accountant in March or April, those doors are already closed.By the time you are sitting across from your accountant during filing season, they are also buried under returns, extensions, and deadlines. That is not when you will get proactive, thoughtful planning. That is triage mode.
The right approach starts earlier. After filing, once the dust settles, schedule a check-in with your advisor or accountant. Ask them directly: based on what I owed, how should I adjust my W-4 withholding? Do I need to make estimated tax payments this year? Do I have any positions with embedded gains I should be thinking about? That one conversation can save you from repeating the same outcome next April.
A practical starting point: the IRS offers a free Tax Withholding Estimator at IRS.gov/W4App. It is specifically designed for situations like dual-income households and multiple income sources, and it can help you identify whether your current withholding is on track before you ever speak to an advisor.
I also recommend a follow-up check-in with your advisor or accountant in September. Not a full tax return. Just a pulse check. Share a recent pay stub, your expected RSU vesting schedule, any anticipated bonuses, commissions, or investment sales. Let your advisor run the numbers. Are you on pace to hit safe harbor? Are there gains that could be offset before year-end? Is there anything you can still do before December 31st?
What Can You Actually Do Before December 31st?
This is where year-round planning really pays off. There are meaningful moves available to you before the calendar year closes, but they require action during the tax year:- Maximizing contributions to a traditional IRA or 401(k) can reduce your adjusted gross income. Note that 401(k) contributions must be made by December 31st and cannot be made retroactively.
- If your income is near a phase-out threshold, those contributions could preserve eligibility for certain tax credits, such as the child tax credit, which begins to phase out at higher income levels.
- Tax loss harvesting, the practice of selling positions at a loss to offset realized capital gains, must be completed before December 31st and can meaningfully reduce your tax bill if done with proper planning.
- Strategically timing deductions or income deferrals may help you land in a more favorable bracket and reduce exposure to surtaxes like the Additional Medicare Tax and the Net Investment Income Tax.
A Proactive Tax Planning Approach Changes Everything
The thread that connects all of these issues is the same: they are all problems that can be managed during the year, and they all become much harder or impossible to fix once the year is over. In our experience at SYKON Capital, the clients who avoid these surprises are not necessarily the ones with the simplest financial lives. They are the ones who are checking in proactively, communicating changes early, and working with advisors who are looking at the full picture year-round.Having Enrolled Agents on our team means we can sit in the same conversation as your accountant, review mock tax projections, identify withholding gaps, and flag potential issues before they become tax bills. Whether you work directly with our team on the tax planning side or you have an outside accountant you trust, we can help coordinate the planning, run the projections, and make sure you have a clear picture of where you stand throughout the year.
Taxes are one of the largest financial levers most people have. The best time to pull that lever is not when you are already writing the check. If this year's tax bill caught you off guard, it may be a good time to have that conversation.
