Mid-Year Tax Planning Checklist for Business Owners (2026)

Most tax planning happens in December, which is when the fewest options remain. Retirement plans that had to be adopted by year end, entity elections with March deadlines, and accounting method changes that take months to prepare are all decided by then.

Mid-year is when the work should happen. Here is what to review while the year is still changeable.

One: Project the Full Year Now

Everything else depends on this. Take six months of actual results, project the remainder, and compute an estimated taxable income and tax for the year.

The projection does not need to be precise. It needs to be close enough to tell you which bracket you are landing in, whether you are above or below the qualified business income threshold, whether you will cross the net investment income tax threshold, and how far you are from any relevant cliff.

Without this number, every subsequent decision is a guess.

Two: Confirm the Estimated Tax Safe Harbor

Compute the safe harbor amount under IRC Sec. 6654: 100% of prior year tax, or 110% if prior year adjusted gross income exceeded $150,000.

Compare it to what you have actually paid through the June installment. If you are short, correct it now rather than in December.

Note that withholding is treated as paid ratably across the year under IRC Sec. 6654(g), so a year-end withholding increase can still cure earlier shortfalls. Estimated payments cannot.

Three: Reassess Reasonable Compensation

If your S corporation income is running well above or below prior year, the salary set in January may no longer be defensible or optimal.

Above the QBI income threshold, salary drives the W-2 wage limitation and cutting it can cost more in lost deduction than it saves in payroll tax. Below the threshold, the calculus reverses.

Adjusting salary at mid-year is straightforward. Adjusting it in December means either a large catch-up payroll or an indefensible full-year number.

Four: Decide the Retirement Plan Before the Deadline

A new 401(k) generally must be established by the end of the tax year to allow employee deferrals for that year, though the SECURE Act permits certain plans to be adopted by the return due date for employer contributions only.

A safe harbor 401(k) has an earlier deadline still, generally requiring adoption before October 1 for a new plan covering the current year.

A defined benefit or cash balance plan requires an actuarial study, plan document drafting, and often a census analysis, which takes weeks. Starting in December means starting for next year.

If a plan upgrade is on the table, the decision belongs in July.

Five: Review Equipment and Fixed Asset Timing

Identify what you plan to buy in the next twelve months and decide which side of December 31 each purchase belongs on.

Remember that the deduction follows the placed in service date, not the payment date, and that financing does not reduce the deduction. A December delivery with 10% down produces the same write-off as a cash purchase.

Decide between Sec. 179 and bonus depreciation deliberately. Sec. 179 gives asset-level control and cannot create a loss. Bonus applies by class and can. State conformity often decides it.

Six: Model Any Cost Segregation Study

If you acquired or improved real property in the last several years, determine whether a study is worthwhile and, critically, which year it should land in.

A look-back study with Form 3115 can place a catch-up deduction in any open year, which means the deduction can be timed against a high-income year rather than taken reflexively at acquisition.

Studies take four to eight weeks. Commissioning one in mid-July leaves room to have it in hand well before the return.

Seven: Check the Pass-Through Entity Tax Election

If you operate in a state with a PTET election, confirm whether the election has been made and whether the entity has made the required estimated payments.

For a cash method entity, the federal deduction lands in the year of payment. Paying by December 31 captures it a year earlier than paying with the return.

Some states have election deadlines well before the return due date, and missing them forfeits the benefit for the year entirely.

Eight: Review Entity Structure Against Current Facts

An S corporation election requires Form 2553 filed generally within two months and fifteen days of the beginning of the tax year for which it is effective. Late election relief exists but is not automatic.

If you are converting from a sole proprietorship or a partnership, the decision belongs early in the year, not at filing.

Similarly, if you have added a business line, a property, or a partner, review whether the current structure still fits before it becomes a multi-year problem.

Nine: Confirm Worker Classification

Review your contractor roster against your employee roster. Anyone doing substantially the same work under substantially the same conditions should be classified the same way.

Section 530 relief requires consistent treatment of similar workers, and inconsistency is the most common way businesses lose it.

Fixing a classification prospectively at mid-year is far cheaper than defending it later.

Ten: Review Accountable Plan and Reimbursements

Confirm that home office, vehicle, cell phone, and travel reimbursements are running through a documented accountable plan rather than being deducted personally, which is not available to employees including S corporation owners.

Reimbursements should be substantiated and paid on a regular schedule, not booked as a lump entry in December.

Eleven: Update Basis and Suspended Loss Records

Maintain basis, at-risk amounts, and suspended passive losses by activity. These records determine what you can deduct and, on a future disposition, what releases.

Property-level suspended loss records specifically preserve partial disposition relief under Treasury Regulation Sec. 1.469-4(g), which aggregate-only records forfeit.

Reconstructing years of records at the moment of a sale is expensive and often incomplete.

Twelve: Plan Charitable Giving Deliberately

If you intend to give, decide now whether to give cash, appreciated securities, or appreciated real property, and whether to bunch multiple years into one through a donor advised fund.

Appreciated assets held more than a year generally produce a fair market value deduction with no gain recognition, which is substantially better than selling and donating cash.

Contributions of property above $5,000 generally require a qualified appraisal under IRC Sec. 170(f)(11), which takes time to obtain and is a common December failure.

Frequently Asked Questions

Why plan at mid-year instead of December?

Because most of the meaningful options have deadlines before or at year end. Safe harbor 401(k) adoption, S corporation elections, defined benefit plan setup, PTET elections, and cost segregation studies all require lead time that December does not provide.

What is the single most important mid-year item?

A full-year income projection. Everything else, salary optimization, plan selection, equipment timing, and study timing, depends on knowing approximately where you will land. Without it every other decision is a guess.

When do retirement plans need to be established?

A safe harbor 401(k) generally requires adoption before October 1 for a new plan covering the current year. Defined benefit and cash balance plans require actuarial work taking weeks. Starting the conversation in December generally means starting for the following year.

Can I still change my S corporation salary at mid-year?

Yes, and mid-year is the right time. If income is running well above or below prior year, the January number may no longer be optimal or defensible. Adjusting in December requires either a large catch-up payroll or an indefensible annual figure.

Is it too late to run a cost segregation study in December?

Usually tight. Studies take four to eight weeks from engagement to delivery. More importantly, a look-back study with Form 3115 lets you place the deduction in the year that needs it, so the timing decision should be deliberate rather than driven by a deadline.

Mid-Year Tax Planning Checklist for Business Owners