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Self-Employed on Long Island? Your Year-End Tax Checklist and the January 15 Payment

By Peter Goldfarb, Enrolled Agent · October 26, 2026 · 5 min read

If you run your own business, nobody is withholding tax from your income. You carry that job yourself, and the end of the year is when it pays to take a look at where you stand. These are the things I walk Schedule C clients through each fall.

The fourth-quarter estimated payment

The last 2026 federal estimated tax payment is due January 15, 2027. In general, you need to make estimated payments if you expect to owe $1,000 or more after withholding and credits.

The usual way to avoid an underpayment penalty is the safe harbor: pay at least the smaller of

• 90% of your 2026 tax, or
• 100% of your 2025 tax (110% if your 2025 adjusted gross income was over $150,000).

New York has its own estimated tax payments for state income tax, so a federal payment alone does not cover it.

A year-end checklist for Schedule C filers

1. Get the books current. Reconcile your bank and card accounts through the end of the year. It is much easier in November than in March.
2. Look at your profit so far. A quick year-to-date profit-and-loss tells us whether your estimated payments are on track, or whether a big year or a slow one means adjusting.
3. Think before large purchases. Equipment, vehicles, and other big-ticket items can change your tax result, and the depreciation rules have shifted in recent years. Call before you buy, not after.
4. Retirement contributions. Some plans must be set up before December 31 to count for 2026, while others allow contributions later. The right option depends on your income and whether you have employees, so ask early.
5. Home office. If you work from home, you can use the simplified method at $5 per square foot (up to 300 square feet) or track actual expenses. Either way, the space needs to be used regularly and exclusively for business.
6. Mileage and vehicle records. A log kept during the year holds up far better than one rebuilt from memory.
7. Contractors and employees. If you paid anyone as a contractor, gather their W-9 information now. Forms 1099-NEC and W-2 are due at the end of January; in 2027, January 31 falls on a Sunday, so the deadline moves to Monday, February 1.
8. Payroll and sales tax. If you file either, make sure the year-end filings and reconciliations are on your calendar so they do not collide with tax season.

Why this matters

None of this is complicated on its own, but it adds up. A small adjustment in December can save real money, and a missed payment can mean penalties. I handle Schedule C returns every year, along with tax projections, payroll, and sales tax filing, so if you want a quick look at where you stand before year end, call or text me.

This article is general information, current as of October 26, 2026, and is not tax, legal, or financial advice for your specific situation. Tax rules change, so please check with a professional before acting.