Every year, without fail, I get the same phone call around this time.
It comes from a business owner. Generally it is someone smart, driven, and genuinely successful. They have been heads-down building their company, managing their team, and handling the hundred other things that quietly devour a founder’s calendar. Then one afternoon, usually while scrolling through emails they’ve been ignoring, they stumble across a subject line that makes their stomach drop.
It says something like “Tax deadline approaching, I’m not ready to file… can we extend” and suddenly the question isn’t about revenue or payroll or growth strategy anymore. The question is: did I miss something?
Chances are, they didn’t miss everything. But chances are also good that there are still a few moves left on the table. Genuine moves that require action now, not in April.
That’s what this article is about. Not panic. Not regret. Strategy.
Over the years, I’ve worked with business owners across the United States — from solo consultants and real estate investors to multi-location operators and professional service firms. And the single most expensive mistake I see isn’t a bad deduction or a missed form. It’s the belief that tax planning has one season. It doesn’t. But as filing deadlines close in, that window does get narrower. And the tools that remain are specific.
So let’s talk about what’s still available, how extensions actually work, and — most importantly — where people accidentally make things worse instead of better.
The Clock Is Real, But the Game Isn’t Over
Here’s something most people don’t realize until they’re sitting across from me at a strategy session: even after December 31st has come and gone, there are still legitimate ways to reduce your 2025 taxable income. The IRS doesn’t slam every door shut on January 1st.
That said, the doors are closing. And some of them don’t reopen.
The key distinction I make with every client right now is this: we are no longer in redesign mode. We can’t restructure the year. What we can do is optimize what’s still available — and use the tools that remain with precision.
Think of it like the fourth quarter of a close game. The playbook is smaller. The margin for error is tighter. But winning is absolutely still possible — if you know your options and act on them quickly.
That’s the mindset I bring into every conversation at this stage of the tax year. Not “what should you have done in June,” but “what can we still do right now?”
Retirement Contributions: The Door That’s Still Open (For Now)
One of the most powerful tools still available to business owners at this stage involves retirement contributions — and the deadline for some of these is later than most people expect.
If you operate as a sole proprietor, a single-member LLC, or an S-Corp with self-employment income, you may still be able to fund a SEP-IRA for 2025. The contribution deadline for a SEP-IRA is your tax return due date, including extensions. That means if you file a timely extension, you can contribute — and deduct — up to 25% of net self-employment income, with a 2025 cap of $70,000 per IRS Publication 560. That’s not a small number.
Solo 401(k) plans are a slightly different story. Contributions to a Solo 401(k) generally require that the plan itself was established by December 31st of the tax year. If yours was set up in time, your employer contribution can still be made by the return due date. Employee deferrals, however, needed to happen before year-end. This is one of those details that separates proactive planning from scrambling.
Defined benefit pension plans — often used by high-earning business owners who want to shelter significantly more income than a SEP or 401(k) allows — also have contribution deadlines tied to the return due date. These plans are complex and require actuarial support, but for the right client, the potential deduction can reach six figures.
The point here isn’t to overwhelm you with plan names. The point is that retirement vehicles are one of the few remaining levers that actually reduce your 2025 taxable income — even in 2026. If you haven’t had this conversation with your tax advisor yet, this is the week to make the call.
Health Savings Accounts and the Deduction Most Owners Miss
If you were enrolled in a High Deductible Health Plan (HDHP) during 2025, you have until the tax filing deadline — including extensions — to make your HSA contribution for that year.
For 2025, the IRS allows individual HDHP enrollees to contribute up to $4,150, and families up to $8,300. Those 55 or older can add an extra $1,000 as a catch-up contribution, per IRS Revenue Procedure 2024-25.
What makes an HSA particularly attractive for business owners isn’t just the deduction. It’s the triple tax advantage: contributions are deductible, growth is tax-free, and withdrawals for qualified medical expenses are also tax-free. No other account in the tax code does all three.
I’ve had clients look me dead in the eye and tell me they “don’t do HSAs” because they think it’s complicated. It’s not. If you had an HDHP last year, contributing to an HSA right now — before you file — is one of the cleanest, simplest deductions left on the table. Don’t leave it sitting there.
S-Corp and Employer-Level Adjustments That Still Apply
For business owners operating as S-Corporations, a few strategic adjustments can still be made before or alongside filing — depending on the specifics of your situation.
One that comes up frequently is the treatment of health insurance premiums for more-than-2% shareholders. If you own more than 2% of your S-Corp and the corporation paid your health insurance premiums, those premiums should be included in your W-2 wages — but they’re also deductible on your personal return as self-employed health insurance. If this wasn’t handled properly on your W-2, it’s not too late to correct. A well-timed amended W-2, processed before filing, can make a real difference.
Reasonable compensation reviews are another area I revisit at this stage. The IRS requires that S-Corp shareholder-employees receive a reasonable salary before taking distributions. If 2025 compensation was set too low relative to the work performed, now is the time to review and document the rationale — not after an audit notice arrives.
Accountable plan reimbursements are also worth reviewing before filing. If your S-Corp has a properly structured accountable plan in place, per IRS Publication 463, business expenses paid from personal funds during 2025 can still be submitted for reimbursement. Those reimbursements are deductible to the corporation and tax-free to you as the employee. The IRS is clear that reimbursements must be substantiated and returned if not business-related, but when done correctly, this is one of the cleanest planning tools available.
How to File a Tax Extension — and Why Most People Misunderstand It
Let’s talk about Form 4868 — the individual tax extension — because this is where I see the most confusion, and unfortunately, the most avoidable penalties.
Filing an extension for your personal return is simple. You submit Form 4868 by April 15th, and your filing deadline automatically moves to October 15th. No approval needed. No explanation required. The IRS grants it automatically.
Here’s what most people miss: the extension is for filing, not for paying.
I cannot say that clearly enough. An extension gives you more time to complete and submit your return. It does not give you more time to pay what you owe.
If you expect to owe taxes for 2025, that payment is still due on April 15th — regardless of whether you file an extension. Underpaying by that date triggers interest and potentially a failure-to-pay penalty under IRC Section 6651(a)(2), which accrues at 0.5% per month on the unpaid balance.
So what should you actually do? Estimate your tax liability as accurately as possible before April 15th. Pay the estimated amount when you file the extension. Then use the extra time to gather documents, review your return thoroughly, and make any final strategic decisions — like funding that SEP-IRA mentioned earlier.
Used this way, an extension is a powerful tool. Used as a way to avoid thinking about your taxes until October, it becomes a very expensive delay.
For S-Corporations and partnerships, the extension form is Form 7004, which I covered in detail in a recent piece on the March 16th deadline. The same principle applies: file by the original due date, and your filing window extends to September. Any tax owed at the entity level is still due on the original deadline.
The Real Cost of Treating Taxes Like a Once-a-Year Event
I want to close with something that goes beyond forms and deadlines, because this is the conversation I find myself having most often — and the one that tends to have the most lasting impact.
Most business owners treat taxes the way they treat a dental cleaning: something you deal with once a year, slightly uncomfortable, ideally over quickly. They show up in March or April, hand their accountant a folder of documents, and spend the next eleven months not thinking about it.
That approach works fine — right up until it doesn’t. And when it doesn’t, it tends to hurt.
The business owners I’ve worked with who consistently pay the least in taxes aren’t the ones with the best accountants. They’re the ones who treat tax planning as a continuous strategy, not a seasonal chore. They make retirement contributions throughout the year and track expenses in real time. They have quarterly conversations with their advisor. and don’t wait for a document to trigger the conversation — they initiate it.
The good news is that you don’t have to be perfect at this. You just have to be more proactive than you were last year.
Right now, in early 2026, there are still meaningful moves available for your 2025 tax year. Retirement contributions, HSA funding, S-Corp adjustments, and the strategic use of extensions can all reduce what you owe — or at least ensure you’re not paying penalties you didn’t have to.
But these moves require action. Not in April. Not when the extension runs out. Now.
Pulling It All Together
Here’s what I want you to walk away with from this article:
Tax planning has a clock, but it’s not over yet. If you’re a business owner, you likely still have access to retirement contribution deductions through SEP-IRAs, Solo 401(k)s, or pension plans. Or, if you were enrolled in an HDHP, your HSA window is still open. If you operate as an S-Corp, there are employer-level adjustments worth reviewing before you file. And if you need more time, a properly filed extension buys you runway — as long as you understand it doesn’t delay your payment obligation.
The mistake I see most often isn’t a complex one. It’s simply waiting too long to ask the question. If you’re still unsure what’s available for your specific situation, the best time to find out was three months ago. The second-best time is today.
If you’d like to explore what’s still possible for your 2025 return, I’d encourage you to schedule a free strategy session with my team at Weston Tax Associates. We work with business owners all over the country, and this is exactly the kind of conversation we have every day at this time of year.
Welcome to the New Age of Accounting. Let’s begin.
P.S. If you found this article helpful, you’ll love my new book S-Corp Mastery: How Smart Business Owners Maximize Tax Savings & Build a Lasting Legacy. It’s now live and available in a sleek, easy-to-read PDF version. Grab your copy here
Chris is the Managing Partner at Weston Tax Associates, a best-selling author, and a renowned tax strategist. With over 20 years of expertise in tax and corporate finance, he simplifies complex tax concepts into actionable strategies that drive business growth. Originally from Sweden, he now lives in Florida with his wife and two sons.
