December closings, and why the preparation window is shorter than it looks

If you intend to close on an aircraft before the end of the year, the preparation window is shorter than the calendar makes it look. The inspection alone can run four to six weeks before anyone has fixed anything, and appearance work done inside that window stops being preparation and becomes a discrepancy.

This is a scheduling article, not a tax one. We will touch the tax position in one paragraph because it sets the deadline, and then leave it to the people who do that for a living.

Why December is still December

Under the One Big Beautiful Bill Act, 100 percent bonus depreciation under Section 168(k) is restored with no scheduled sunset, applying to qualifying property acquired under a binding contract on or after 19 January 2025 and placed in service after that date. The practical effect is that the old annual step-down, which drove a scramble every autumn to beat a falling percentage, is gone.

What has not gone is the placed-in-service date. If the deduction is wanted in a given tax year, the aircraft has to be in service in that year. So the December cluster is still real, just for a narrower reason than it used to be. Your tax counsel owns that question and nothing in this article is advice about it.

Count backwards from the closing, not forwards from today

The only published durations we could find from a major maintenance provider come from West Star Aviation, which puts the physical pre-purchase inspection at 10 to 12 business days, explicitly excluding the correction of discrepancies, and the records review at 12 to 15 business days depending on the age of the aircraft.

Read that carefully. Those two can overlap, but the longer of them is three weeks of business days before anyone picks up a tool to fix what was found. Then discrepancy correction, which West Star says cannot be scoped until the discrepancies are known.

West Star also makes a point that matters more than the numbers: there is no standard pre-purchase inspection. A pre-buy “is not designed to find every discrepancy, it’s designed to give the buyer a general overview of the current condition of the aircraft,” and every facility develops its own checklist. So any timeline you are given is that facility’s timeline for that aircraft, and the only useful version of it is the one in writing from the shop that will actually do the work.

Duncan Aviation, writing on the same subject, declines to give a duration at all and instead warns against rushing, which is its own kind of answer.

Where appearance work actually belongs

Before the aircraft goes to the inspection. Not during, and not after.

There are three reasons, and only one of them is about how the aircraft looks.

An inspector cannot assess what is covered. A belly under baked exhaust soiling, wheel wells with accumulated deposits, flap and hinge areas that have not been cleaned, these do not read as clean to an inspector. They read as unverified, and unverified goes in the report.

Hangar time at a pre-buy is the most expensive hangar time in the transaction. Every day the aircraft is sitting in an inspection facility is a day of someone’s schedule, and work that could have been done in advance at a base rate gets done at the worst possible moment, if it gets done at all.

Timing changes what the work is called. Appearance work completed before listing is maintenance. The identical work identified during a pre-buy is a discrepancy on a list that the parties are negotiating over. Same labour, different column.

A workable shape for a 31 December closing

We are not going to give you a week by week plan, because the honest answer is that it depends on the aircraft, the shop and what the inspection finds, and anybody handing you a confident calendar has not asked those questions. What we would say is this.

Work backwards from the closing date through discrepancy correction, then through the longer of the physical inspection and the records review, then add whatever slack the shop tells you they need at that time of year. Shops are busy in Q4 for the same reason you are.

Then put appearance work before all of it. Not in the gap you find later, because there will not be one.

If that arithmetic puts your start date earlier than feels comfortable, that is the arithmetic telling you something true. The usual failure is not that someone forgot. It is that the inspection ran longer than planned, the discrepancy list was longer than hoped, and the thing that got cut was the preparation, because it was the only item on the list without a regulatory requirement behind it.

One more thing worth knowing

NBAA publishes an Aircraft Transactions Guide, updated in 2026, developed by its Tax Committee and Aircraft Transactions Working Group. It is members only, so we are not going to characterise what is in it. If you are doing this more than once, it is the obvious place to start and membership costs less than one day of unplanned hangar time.