Tax preparation reports the year you had. Tax planning changes it. The difference is entirely a matter of timing: once December 31 passes, most of what could have been decided is closed, and your preparer is left recording decisions someone else already made.
Here is what is genuinely still open before year end, and what is not.
Estimated payments: the deadline most owners get wrong
If you are self-employed or your income does not have tax withheld from it, you pay as you go. Estimated tax payments are generally due April 15, June 15 and September 15 of the tax year, and January 15 of the following year.
The penalty for underpaying is avoidable, and the rule for avoiding it is specific. You generally escape the underpayment penalty if you paid at least:
- 90% of the tax shown on this year's return, or
- 100% of the tax shown on last year's return, whichever is less.
If your prior-year adjusted gross income was more than $150,000 — or $75,000 if married filing separately — that 100% becomes 110%. Separately, most taxpayers avoid the penalty if they end up owing less than $1,000 after withholding and refundable credits.
The practical point: the prior-year figure is known. It is on a return that already exists. A business with a good year can protect itself from the penalty by paying against last year's number rather than guessing at this year's — and that is a decision, not a calculation.
What timing actually controls
Within the rules, a business has some control over which year income and expenses land in. Accelerating a deductible purchase into December or deferring an invoice into January changes which year the tax falls in.
Two cautions, because this gets oversold. First, timing moves tax between years — it rarely eliminates it, and pulling deductions forward can leave next year thin. Second, whether you can shift an item at all depends on your accounting method, which is not something to change casually. This is a conversation to have with your corporate tax preparation in October, not a trick to apply in December.
Entity structure, and why it is a planning question
Whether you operate as a sole proprietor, an LLC, an S-Corp or a C-Corp affects how profit is taxed, what payroll obligations you carry, and what paperwork the year requires. It is a genuine planning decision with real consequences in both directions.
What it is not is a universal answer. The advice that a particular structure always saves money is wrong often enough to be dangerous, because the right answer depends on your profit level, whether you take a salary, how many owners there are, and what you intend to do with the business. If you are weighing it, weigh it with your actual numbers — and note that changing structure has its own timing rules. We work through this when we incorporate a business in Florida.
The deduction that depends on your structure
Owners of sole proprietorships, partnerships, S corporations and some trusts and estates may be eligible for the qualified business income deduction — the Section 199A deduction — of up to 20% of qualified business income, plus 20% of qualified REIT dividends and qualified publicly traded partnership income.
It is worth naming here rather than in a preparation article because eligibility and the amount interact with how you are structured and what you pay yourself. That makes it a planning input, not a line you discover in April. It also has limitations and thresholds that this paragraph is deliberately not summarising, because the summary version is where people go wrong.
Retirement contributions as a planning lever
Funding a retirement plan is one of the few moves that reduces current taxable income and keeps the money. For 2026 the basic 401(k) limit is $24,500, with an additional $8,000 catch-up at 50 and older, and a higher $11,250 catch-up for ages 60 through 63.
For an owner, the question is not only how much but through which plan, and plan choices have their own establishment deadlines that fall before you file. The retirement side of this is worth reading in full.
What Florida does and does not change
Florida has no personal income tax, which removes one whole layer of planning that owners in other states spend time on. It does not remove federal income tax, self-employment tax, payroll obligations, or Sales Tax if you sell taxable goods — and sales tax has its own registration thresholds and filing calendar that catch growing businesses. That is covered in our guide to Florida sales tax.
What planning cannot do
Planning changes the timing and structure of decisions you were going to make anyway. It does not make a purchase you did not need worth making, and a deduction is never worth more than the dollar you spent to create it. Any advice that starts with buying something in order to save tax is worth examining slowly.
The rules above reflect IRS guidance current as of July 2026 and are general information. Whether any of it applies to your business depends on facts this article does not know.
Have the conversation in the fourth quarter, not in April
Bring your year-to-date profit and loss, last year's return, and what you expect the rest of the year to look like. We will tell you where you stand against the estimated-payment safe harbor, what is still moveable before December 31, and what genuinely is not. Start with corporate tax preparation, or call +1 (954) 724-1114.