Tax Tips

Most tip lists are organized by who you are. This one is organized by when the door closes, because that is the part that decides whether a tip is worth anything to you today. Nearly everything that lowers a tax bill has to happen inside the tax year. Once the calendar flips, you are no longer planning — you are reporting.

Before December 31 — the real deadline

These are the moves that stop being available at midnight on the 31st. If you read only one section, read this one.

• Max the plan you already have. The 2026 elective deferral limit for a 401(k), 403(b), or 457(b) is $24,500, plus an $8,000 catch-up at 50 and $11,250 at ages 60 through 63. Deferrals come out of payroll, so “I’ll do it in April” does not exist — the last paycheck of the year is the last chance.
• Check whether you have a second plan available. If you have W-2 income and 1099 income, the §415(c) cap of $72,000 generally applies per plan, not per person. A solo 401(k) alongside a hospital 403(b) is the most commonly missed opportunity I see.
• Decide on a Roth conversion while you can still see the year. A conversion is a December decision made with November information: you know roughly what your income was, and you know what bracket space is left. In April you are just reporting what happened.
• Harvest losses deliberately, not reflexively. Realized losses offset realized gains, and up to $3,000 of ordinary income beyond that. Watch the wash sale rule — repurchasing a substantially identical position within 30 days on either side disallows the loss.
• Make charitable gifts before the year ends, and get a contemporaneous written acknowledgment for anything $250 or more. Appreciated stock held over a year is usually a better gift than cash: you deduct the fair market value and never realize the gain.
• Buy the equipment you actually need, if you need it. Section 179 and bonus depreciation can accelerate the deduction, but the asset has to be placed in service by year end. Buying something you do not need to save 30 cents on the dollar is not a strategy.
• Look at your withholding one more time. Withholding is treated as paid evenly across the year no matter when it actually happened, which means a December adjustment can fix an underpayment that occurred in March. An estimated payment cannot do that.

January through April — the short list that’s still open

A few things genuinely can still be done after the year ends. Not many.

• IRA and HSA contributions for the prior year can be made up to the April filing deadline. The 2026 IRA limit is $7,500, plus $1,100 at 50 and over.
• A SEP-IRA can be funded as late as the extended due date of the return, which makes it the one meaningful retirement lever still available in September.
• Gather documents once, completely. The single biggest cause of a slow return is a second and third round of “can you also send…” Prior-year return, every W-2 and 1099 and K-1, mortgage interest, property tax, tuition statements, and anything unusual about the year.
• File an extension if you need one, and pay with it. An extension moves the filing deadline, never the payment deadline. The failure-to-file penalty is roughly ten times the failure-to-pay penalty, so extending is almost always right — just send an estimate of what you owe along with it.

Any time of year

• Separate business and personal money completely. One dedicated account and one dedicated card. This does more for the defensibility of your deductions than any single other habit, and it cuts bookkeeping time in half.
• Keep contemporaneous records, not reconstructed ones. Mileage logs and home office documentation written at the time hold up. The same information reconstructed from memory in March is the most common weak point in a small business examination.
• Revisit your entity as the business changes. The right structure at formation is often the wrong one three years later. The S-corp election in particular has a hard March 15 deadline for the current year — deciding in November that you wish you had elected is a much worse position than deciding in February.
• Update your W-4 after anything changes. A marriage, a divorce, a second job, a new child, a spouse going back to work. The form was redesigned and no longer uses allowances, which means the mental model most people have for it is out of date.
• Treat 1099 income as a business, because it is one. Moonlighting, locums, expert witness work, consulting — all of it carries self-employment tax, quarterly estimates, and a set of deductions that a W-2 does not. Folding it into a normal return is where people both overpay and get surprised.
• Open the mail from the IRS. The response deadline runs from the date printed on the notice, not the date you got around to it, and most notices are automated matching that resolve in writing. Ignoring one is how a small correction becomes a collection issue.

Read out of Notice 2025-67 in September 2026. Current for tax years 2025 and 2026. If you are relying on one, confirm it at the source.