September closes out with one last practical checklist, this time focused specifically on what needs to happen with your books before the calendar flips to a new year. Getting ahead of this now means January looks like a clean transition instead of a scramble.

Make sure every account is reconciled through September, with no backlog carrying forward into Q4. Starting the last quarter of the year with clean books makes everything from here forward easier, from tax planning to the scenario forecasting we've talked about this month.

Confirm your Q3 estimated tax payment was made and start calculating what Q4's payment, due in January, is likely to look like based on your actual year-to-date profit, not a rough guess.

Review your chart of accounts and tracking categories to make sure everything is still set up in a way that reflects how the business actually runs today. A lot of businesses grow and change during the year without ever revisiting whether their books are still structured to match, and Q4 is a good checkpoint to fix that before year-end reports get pulled.

Start collecting W-9 forms now for any subcontractors you've paid $600 or more this year, so 1099 preparation in January is a matter of confirming information you already have, not chasing down paperwork under deadline pressure.

Think through any year-end tax strategies that make sense given how the year has actually gone, whether that's an equipment purchase that makes operational sense and also helps with depreciation, or increasing retirement contributions if profit has been strong.

Update your cash flow forecast through year-end and into Q1, since the slow season conversation we've had all month matters just as much heading into January as it does heading into November.

Finally, set a specific date on the calendar to sit down with your bookkeeper before year-end closes, rather than letting it happen reactively once your CPA starts asking for documents in February.

This is the last post in our September calendar, and if there's one thing we hope stuck from the whole month, it's this: the businesses that handle their slow season and their tax season with the least stress are the ones whose books were already in order before either one arrived.

Jeremy Brewer is the founder of 911 Bookkeepers LLC in Baton Rouge, Louisiana. He worked in the field as an HVAC tech before building books for the trades, and he serves as a licensed paramedic in EMS. He is a Xero Certified Advisor.