December 2026: which year-end deadlines are real, and which can wait
It is November. Which of the year-end dates actually require me to do something?
Every November the same pages get read as one list of deadlines. They are not one list. Some are windows that close on a fixed date, some are dates that change which rule applies to something you do later, and some are published numbers that look urgent but only change a comparison. Treating them as the same kind of thing is how people spend December on the wrong task. This guide separates the three, using only the dates and figures the network has already published with sources.
Published November 8, 2026 · 8 network pages · 62 primary sources carried below
The three kinds of date
Windows that close. A date after which an action is no longer available in that cycle. Missing one costs an option, not just time.
Dates that change the rule. A date that decides which set of rules applies to an action you take afterwards. The action may still be possible on both sides of the date; what changes is the treatment.
Published numbers. Figures that arrive in the autumn and look like deadlines. They are not. They change the arithmetic of a decision you will make later.
The pages below fall into these three groups. Read the group you are actually in.
Group 1 — Windows that close
Medicare open enrollment 2027 states the window plainly: October 15 to December 7, 2026. It also reports that average Advantage premiums fall for 2027 while stand-alone drug plans move the other way, and it warns that the averages are exactly where the headline misleads most. Four checks before you switch anything, and a note on the scam season that comes with the window.
The ACA Marketplace gives a different calendar: open enrollment runs November 1 to January 15. It explains how subsidies work since the enhanced credits expired, the return of the 400% cliff, where Medicaid fits, and what is not compliant coverage. The companion page on the 2027 subsidy cliff adds the published 2027 income lines and contribution rates, four changes that ride along with the reversion, and an explicit warning not to plan around a bill — the legislative status was live when it was written.
Two different windows, two different populations, four days apart at one end and five weeks apart at the other. Conflating them is the most common November mistake. Check which one you are in before reading either page’s advice about what to switch.
The 1% student loan auto-pay discount is a third kind of closing window: the Department of Education extended the auto-pay interest rate reduction deadline to December 31, 2026. The page covers who qualifies, what borrowers in default must do first, what the benefit is worth, and one warning worth repeating — enrollment is free.
Finally, Year-End Money Moves draws the line the whole group depends on: most tax moves expire with December 31, but retirement and health account contributions get until the filing deadline. The page’s own framing is that sorting those two lists is the entire exercise. It also names the quieter one — the MAGI deadline that costs money without announcing itself.
Group 2 — Dates that change the rule
The new opportunity zones is the clearest example. Treasury designated 6,576 tracts on November 5, 2026, and which rules apply depends on one date: money invested after December 31 gets a five-year deferral and a 10% or 30% step-up. Nothing stops on January 1. What stops is one version of the treatment. The page also asks whether you can still use a gain realized in 2026, and how to check a property against the designation list.
Medicare’s 2027 negotiated drug prices is the same shape from the other direction. Fifteen more Part D drugs get negotiated prices on January 1, 2027, while four first-round drugs leave the program. The page is careful about what a “maximum fair price” is and is not, and it names the other January 1 change that runs the other way. A formulary check in December and the same check in January are not the same check.
These two are why “year-end deadline lists” are misleading. Nothing about them requires action by December 31; what they require is that you know which side of the date your action falls on.
Group 3 — Published numbers, not deadlines
The IRS’s 2027 figures arrived on November 5, 2026. The seven rates did not change; what moved is the income level at which each rate starts, and the standard deduction and gift limits. The page makes the distinction that decides most of the confusion: those 2027 amounts generally apply to returns filed in 2028, not to the return you file in early 2027. It also works out what a roughly 3% shift in the brackets is actually worth on a stated salary, and lists what stayed frozen.
Read this group when you are deciding something, not when you are clearing a to-do list. The numbers are inputs to the December choices described on that page — they are not a clock.
How to use this in ten minutes
Write down every November or December item you think is a deadline. Put each in one of the three groups. Anything in Group 1 gets a date on a calendar. Anything in Group 2 gets a note about which side of the date your action falls on. Anything in Group 3 gets moved out of the deadline list entirely.
If you want the mechanical version, the hub’s effective-dates calendar lists the published rule-change rows, and its calendar export carries the same rows into a calendar application.
What this guide does not settle
It does not decide which window you personally are in, whether a plan or a loan is available to you, or what any of these figures mean for your own return. The eight linked pages carry those answers and the primary sources behind them; the sources are reproduced below so nothing on this page has to be taken on trust.
It also does not track later changes. The subsidy-cliff page already notes that the legislative status was live at the time of writing, and several of these items are rules rather than statutes. Check the linked page, not this guide, before acting on a number.