Year-round habits
- Separate the money. Dedicated business checking and card. Every mixed transaction is a future argument.
- Log mileage contemporaneously. A tracking app beats a reconstructed notebook — the IRS is explicit about vehicle substantiation.
- Photograph receipts at purchase. Thermal paper fades; phone photos don't. Note the business purpose on unusual ones.
- Reconcile monthly. Thirty minutes a month beats thirty hours in March — and it's what makes your books quote-ready.
- Track home-office use. Square footage of the dedicated space, and keep it exclusive — no guest-room double duty.
- File contractor paperwork on time. Collect W-9s when you hire contractors, not in January when 1099s are due.
Year-end moves to discuss with your tax pro
- Retirement contributions. SEP IRA and Solo 401(k) funding — among the largest levers available; deadlines and limits are year-specific.
- Equipment purchases. Section 179 immediate expensing vs. depreciation — timing a purchase in December vs. January changes which year it hits.
- Income and expense timing. Where the rules allow, accelerating deductions or deferring income across the year boundary.
- Inventory and bad debts. Write-downs and uncollectible receivables need to be recognized properly to count.
- Health insurance premiums. Confirm the self-employed deduction is captured — it's easy to miss when nothing changed year over year.
- Estimated payment calibration. True up Q4 estimates so you're neither penalized nor giving an interest-free loan.
These are topics for a planning conversation, not DIY decisions — several interact with entity type and prior elections.
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Deadlines not to miss
- January 31: W-2s to employees, 1099s to contractors (and e-filed copies to the IRS).
- March 15: S corporation (1120-S) and partnership (1065) returns due — or extension filed.
- April 15: Individual, sole proprietor (Schedule C), and C corp returns due — or extension filed. Q1 estimates due.
- Quarterly: estimated payments due mid-April, mid-June, mid-September, mid-January.
- Extensions extend the filing deadline, not the payment deadline — you still must pay what you owe on time to avoid penalties and interest.
Frequently asked questions
When should I start thinking about year-end tax moves?
October through early December is the practical window: late enough to estimate the full year, early enough to act. Retirement contributions, equipment purchases, and income/expense timing all need lead time. Anything discovered in January is mostly history.
What records does the IRS actually want to see?
Records showing amount, date, place, and business purpose for each deduction — receipts, bank and card statements, mileage logs, and invoices. Digital copies are fine. The standard is "adequate records": enough that a stranger could reconstruct what happened and why it was business.
Do quarterly estimated payments apply to me?
If you expect to owe $1,000 or more in tax after withholding and credits, you generally need to pay quarterly estimated tax (Form 1040-ES) to avoid penalties. New business owners are the classic surprise case: nobody withholds from your profit anymore. Safe-harbor rules let you avoid penalties by paying enough based on last year — discuss the math with a professional.