November 10, 2025
Year-end tax planning for 2025: what Colorado owners should do before December 31
The 2025 edition of the only tax checklist with a December deadline. Here are the moves to make before the year closes — while you still can.
Every fall we send clients a version of this reminder, because it is the single most valuable and most ignored fact in small-business tax: almost every move that lowers your bill has to happen by December 31, not April 15. With the 2025 books nearly complete, here is the short list worth running before the year closes.
Start from current, accurate books
You cannot plan on numbers you do not have. Before anything else, make sure your 2025 books are current so you actually know your profit for the year. If a backlog has crept in, that is step zero — and our catch-up bookkeeping guide is the place to start.
Project the year and the tax
With the year nearly done, estimate where 2025 lands and what you will owe. That number drives every other decision — whether to defer income, accelerate expenses, fund retirement, or simply make sure your January estimate is right.
The levers still available before December 31
- Time income and expenses between 2025 and 2026 where you can, especially if your rate differs between the years.
- Equipment purchases placed in service by year-end may be deductible now via Section 179 or bonus depreciation — but buy for the business need, not just the deduction.
- Retirement contributions — funding a SEP-IRA or solo 401(k) is often an owner’s biggest deduction, and some plans must be established by December 31.
- Clean-up — write off genuinely bad debt, record owner items correctly, and capture every deduction you are entitled to.
The Colorado and entity items
For a profitable S-corp or partnership, check whether the Colorado PTE election (the SALT Parity workaround) makes sense for 2025 — it is deadline-sensitive and genuinely valuable. Confirm your S-corp salary was reasonable and actually ran through payroll. And set your final 2025 quarterly estimate so you land inside the safe harbor.
Tax planning is a fall sport. The gap between a 2025 return you dread and one that is just paperwork comes down to decisions made in the next few weeks, not next April.
The bottom line
Get your 2025 books current, project the year, pull the right levers, and check the Colorado-specific items before the window shuts on December 31. If you want a second set of eyes while there is still time to act, a year-end planning call is exactly that.
This is general information for Colorado business owners, not individual tax advice, and the specifics change year to year. Confirm what applies to your 2025 return with a CPA before acting.