Run the numbers before you need them.

1. Fill the pre-tax buckets you actually have

The 2025 limit on employee 401(k) deferrals is $23,500, with an extra $7,500 if you're 50 or older (and a larger catch-up for ages 60–63). A traditional IRA adds up to $7,000; a family HSA another $8,550. Every dollar in those buckets comes off the top of your taxable income at your marginal rate — for a household in the 24% bracket, maxing a 401(k) alone is worth about $5,600 of federal tax. The catch: 401(k) deferrals must come out of paychecks dated in 2025, so a December pay-cycle change is often too late. Check your year-to-date total now and adjust the percentage while there are still pay periods left.

2. Decide whether your business should be an S-corp

If you're a sole proprietor or single-member LLC clearing more than roughly $60,000 of profit, an S-corporation election can save real self-employment tax by splitting income between a reasonable salary and distributions. But the election has to be in place, payroll has to have run, and the salary has to be defensible — none of which can be reconstructed in April. If you're near the threshold, model it before Thanksgiving; if it makes sense, we can have payroll running for December.

3. Harvest losses — and know the trap

Selling investments that are down lets you offset gains you've already realized, and up to $3,000 of ordinary income on top, with any excess carried forward. Two things to get right: the sale must settle by December 31, and you can't buy the same (or a "substantially identical") security within 30 days on either side, or the wash-sale rule disallows the loss. Swapping into a similar-but-different fund keeps you invested and keeps the loss.

4. Bunch your charitable giving

With the standard deduction at $31,500 for joint filers in 2025, many generous households get no tax benefit from their gifts at all. The fix is timing: give two years' worth in one year (a donor-advised fund makes this painless), itemize that year, then take the standard deduction the next. Giving appreciated stock instead of cash adds a second layer — you deduct the full market value and never pay the capital-gains tax on the growth.

5. Run the estimated-payment math one last time

Underpayment penalties are calculated quarter by quarter, so a large January 15 payment doesn't undo a shortfall from June. If you've had a good year — a bonus, a property sale, a profitable side business — the cleanest fix is often to increase withholding on a December paycheck. Withholding is treated as paid evenly through the year regardless of when it actually came out, which quietly erases the earlier quarters' shortfall.

The rule of thumb: if a move needs money to leave your account, a form to be filed, or a trade to settle, it needs to be finished by December 31 — which in practice means decided by early December.

Clean books pass three tests. Every bank and credit-card account reconciles to the statement, to the penny, every month. Every transaction is categorized in a way you could explain to an auditor in one sentence. And the balance sheet makes sense — no negative cash, no "ask my accountant" account with $14,000 sitting in it, no loan balance that hasn't moved since 2023. That's it. Pretty reports and color-coded dashboards are nice, but they're decoration on top of those three things.

Why it's about more than tax

When you apply for an SBA loan, a line of credit or a commercial mortgage, the underwriter reads your books before they read your business plan. Books that don't reconcile signal risk, and risk is priced in — or declined. The same is true when a buyer looks at your business, when a landlord vets you for a lease, or when the IRS asks a question. Clean books are the difference between answering in an afternoon and spending a month reconstructing a year.

The six habits

1. Separate accounts, no exceptions. One business checking account, one business card. The moment personal groceries hit the business card, every transaction becomes a judgment call.
2. Reconcile monthly, by the 10th. Reconciling twelve statements in March takes a weekend. Reconciling one in the first week of the month takes twenty minutes, and errors are still fresh enough to fix.
3. Attach the receipt to the transaction. Modern software lets you photograph a receipt and match it in seconds. A shoebox is not a system; a folder of PDFs named by date is barely one.
4. Keep a fixed-asset list. Anything over $2,500 with a useful life beyond a year — laptops, vehicles, equipment — goes on a list with the date and cost. Depreciation decisions are made from that list, not from memory.
5. Collect W-9s before you pay anyone. Chasing contractors for their tax ID in January is the single most common reason 1099s go out late.
6. Close the month. Once a month is reconciled and reviewed, lock it. Books that keep changing after the fact are books nobody trusts — including you.

What "done" looks like in January

If those habits hold, your year-end package is a profit-and-loss, a balance sheet, a fixed-asset list and twelve reconciled statements. Your return can be prepared from that package without a single question back to you. That's the boring tax season we're after — and it's also exactly what a lender wants to see.

Not there yet? Our Growth plan includes a one-time catch-up and clean-up of the current year, then monthly close from then on. Most owners are current within three weeks.

The default: 27.5 years of small deductions

When you buy a rental, the IRS treats the whole building as one asset that wears out over 27.5 years (39 for commercial). Take a $640,000 duplex. Roughly 20% of the price is land, which never depreciates, leaving $512,000 of building. Straight-line depreciation on that is about $18,600 a year — a useful deduction, but a slow one.

What a study changes

A cost segregation study is an engineering-based report that breaks the building into its parts. Carpet, cabinetry, appliances, dedicated electrical, window coverings and similar items are 5- or 7-year property. Fencing, paving, landscaping and drainage are 15-year land improvements. Only the structure itself — foundation, framing, roof, walls — stays on the 27.5-year schedule.

On our duplex, a study reclassified about 20% of the building cost: $71,700 of 5- and 7-year property and $30,700 of land improvements. Because bonus depreciation lets you deduct 100% of property with a life under 20 years in the year it's placed in service, that $102,400 became a first-year deduction. Add the ordinary depreciation on the remaining $409,600 of structure and the year-one total came to roughly $118,000 — against $18,600 without the study. For a client in the 32% bracket, that's a difference of over $30,000 of federal tax in year one, from a study that cost about $4,000.

When it pays

• You can actually use the loss. Rental losses are passive. They offset other passive income freely, but only offset wages or business income if you qualify as a real-estate professional, run a short-term rental you materially participate in, or fall under the $25,000 active-participation allowance (which phases out between $100,000 and $150,000 of income). A big deduction you can't use this year is just a carry-forward.
• You'll hold for several years. Accelerated depreciation is recaptured when you sell, at rates up to 25% on the building portion and ordinary rates on the 5/7/15-year items. Hold long enough — or exchange under Section 1031 — and the deferral is worth far more than the recapture.
• The building is worth studying. Below roughly $300,000 of building cost, the fee starts to eat the benefit. Above $1 million, it's rarely a close call.

When to skip it

If you're in a low bracket this year and expect a higher one later, front-loading deductions is backwards. If you plan to sell within two or three years without an exchange, recapture will claw back much of the gain. And if you already have suspended passive losses you can't use, adding more helps nobody. In each case, the right answer is straight-line depreciation and a plan to revisit — a study can be done years after purchase with a "look-back" catch-up, without amending old returns.

The Acquire-stage question: before escrow closes, we model the study against your other income and your exit plan. Doing that after closing still works; doing it before lets you choose the entity and the financing with the answer in hand.