Will the FY2027 defense bill (NDAA) become law by December 31, 2026?
We estimate a 75 percent chance the FY2027 defense authorization bill becomes law by December 31, 2026. The main reason: Congress has enacted an NDAA 65 years in a row, usually in December. The main risk: Senate Democrats blocked it 50 to 46 in July over the Iran war, and it has not moved since.
Why it matters: The annual defense bill sets policy and pay for about 1.3 million active-duty troops and their families and authorizes a record $1.15 trillion defense budget, while Senate Democrats are blocking it over the war with Iran.
TPG forecast
75%
Likely
With a real risk of slipping
Version 1: 75% (range 62% to 86%) · Kalshi 85%
Evidence cutoff Sep 26, 2026 · published Sep 26, 2026 · Likely, with a real risk of slipping
This forecast is on its first version. Each update adds a point; old versions are never edited.
The numbers behind the call
65
consecutive fiscal years Congress has enacted an NDAA[7]
8 of the last 10
NDAAs enacted in December[1]
50-46
failed July 14 Senate vote on taking up the bill[2]
216-to-212
House vote passing its $1.15 trillion version[3]
3.6%
troop pay raise in the Senate bill[4]
77-20
final Senate vote for last year's NDAA in December 2025[5]
What it means for you
Service members and military families
The Senate bill carries a 3.6% troop pay raise plus housing, childcare and health provisions. A delay into 2027 would hold up the policy changes and could briefly interrupt bonus and special pay authorities that are usually renewed each year.
Defense workers and contractors
The bill authorizes $1.15 trillion in the House version and $1.14 trillion in the Senate version, and sets acquisition rules, multiyear buys and new programs that contractors plan hiring around.
Taxpayers
The authorized level is the largest ever proposed. Whatever number the final bill carries becomes the marker for defense appropriations, and for the separate $350 billion reconciliation request, in 2027.
People following the Iran war
The bill is the main vehicle for Congress to write limits or reporting requirements on the war that began February 28, 2026. Its fate signals how much say Congress will claim over the conflict.
Voters
The House version carries the SAVE Act voter eligibility measure. Whether that survives into a final bill matters for voter registration rules in future elections.
The read
Three lenses, always in this order. How the method works.
01
Psychology
What do the decision makers need?
Nobody in the defense committees wants to be the leader who ends a 65-year streak. Armed Services Chair Roger Wicker, ranking Democrat Jack Reed, and their House counterparts Mike Rogers and Adam Smith all have careers built on getting this bill done, and they have a proven method: when the Senate cannot pass its own bill, the four leaders write a compromise text and each chamber votes on it. House Chair Rogers said on the floor in July that the House version is 'just a single step in a long process.'
Senate Democrats paid a real price to block the bill before an election, accepting attacks that they held up a troop pay raise. That shows their objection to the Iran war and the spending level is sincere, not a bluff. But their stated goal is leverage over the war and the topline, not the bill's death. After the election, Democrats who expect to gain power in January could choose to wait and write the bill themselves, and that is the scenario that pushes enactment into 2027.
02
History
What happened the last times this came up?
Reference class: the last 20 NDAAs (fiscal 2007 to 2026). Sixteen became law by December 31 of the year their fiscal year began. Four slipped into January: fiscal 2008 (January 28, 2008, after a pocket veto), 2011 (January 7, 2011), 2013 (January 2, 2013) and 2021 (January 1, 2021, after a veto override). That is 80 percent on time by this definition.
Closest analogue: fiscal 2021. A contested election, a lame duck, and a presidential veto over an unrelated demand pushed the final override to New Year's Day. Where it breaks: that bill had passed both chambers by wide margins in the summer. In 2026 the Senate has not even agreed to take up its bill, and the House passed its version by just 216 to 212 after attaching the SAVE Act, a measure the Senate is unlikely to accept. The Senate has skipped its own floor passage before, notably for the fiscal 2023 and 2025 bills, and still finished in December using a negotiated text, so floor failure alone is not fatal.
03
Statistics
Base rate, adjustments, the number.
Start from the 80 percent on-time base rate (16 of 20).
Subtract 10 points for conditions with no clear precedent in the reference class: a live war the minority party opposes, a failed cloture vote on even taking up the bill, a House version loaded with a partisan election measure, and a short lame duck that must also handle appropriations and possibly a war funding package. Add 5 points for the streak's institutional pull and the established shortcut of a leaders' compromise text, which needs no Senate floor passage of S. 4784.
80 minus 10 plus 5 lands at 75 percent, band 62 to 86 percent. Kalshi prices 'Before Jan 1, 2027' at 84 to 87 cents. We are about 10 points lower because a slip of even one day into January resolves NO, and three of the last four slips in the reference class happened in exactly the kind of contested lame duck we expect this year.
Between the lines
What people spent versus what they said, and what was left out.
Costly signal
Senate Democrats voted as a bloc against even taking up the NDAA on July 14, 2026 (50 to 46), with Sen. Tammy Duckworth saying the Senate cannot authorize $1.14 trillion for an 'illegal and disastrous war.'
Blocking a pay-raise bill four months before an election is expensive, so the objection is real. But Democrats targeted the motion to proceed, not the committee bill they helped write 18 to 9. They are bargaining over terms, not trying to kill the bill.
Sequencing
Majority Leader Thune entered a motion to reconsider in July but, per the Congressional Research Service, the Senate took no further step through September, even during the pre-election week.
Leaders are saving the defense bill for a lame-duck package negotiated by the four committee leaders. That is the path used in recent years and it points to December action, which is favorable for YES but leaves little slack before December 31.
What was left out
House Republicans attached the SAVE Act voter eligibility measure to the NDAA text they sent to the Senate.
A rider the Senate cannot pass tells you the House bill is a negotiating position, not the final product. Its presence raises the chance of a late December standoff, because dropping it will be a visible concession for House conservatives.
Tone shift
HASC Chair Mike Rogers promised to 'work in a bipartisan manner as we make our way through the conference committee' even as his bill passed with six Democratic votes.
Committee leaders are signaling that the final bill will be written across the aisle. That tone matches every recent December finish.
Our number after adjusting the base rate for what is different this time: 75%. It sits inside the historical interval.
Check our statistics yourself
- Reference class
- 16 of 20 (80%)
- Exact 95% CI (Clopper-Pearson)
- 56.3 to 94.3%
- Bayesian 95% credible (uniform prior)
- 58.1 to 91.8%
- Binomial test of our 75%
- p = 0.798
Our 75% sits inside the historical interval: the forecast is consistent with how cases like this have gone.
Reproduce in JASP (free, jasp-stats.org)
- Download base-rate.csv (one row per case in the reference class, outcome 1 or 0) and open it in JASP.
- Frequencies, then Binomial Test. Variable: outcome. Test value: 0.75. Tick Confidence interval. JASP reports the same p value and Clopper-Pearson interval shown here.
- Frequencies, then Bayesian Binomial Test, with a Beta(1, 1) prior. The posterior 95% credible interval matches ours.
Reference class: TPG count from enactment dates of each NDAA from fiscal 2007 to fiscal 2026. Late cases: FY2008 (signed January 28, 2008), FY2011 (January 7, 2011), FY2013 (January 2, 2013) and FY2021 (enacted January 1, 2021). Greenberg Traurig notes eight of the last 10 were enacted in December.
Base rate
80%
of the last 20 NDAAs (FY2007 to FY2026) became law by December 31 of the year their fiscal year began (16 of 20)[1][7]
TPG count from enactment dates of each NDAA from fiscal 2007 to fiscal 2026. Late cases: FY2008 (signed January 28, 2008), FY2011 (January 7, 2011), FY2013 (January 2, 2013) and FY2021 (enacted January 1, 2021). Greenberg Traurig notes eight of the last 10 were enacted in December. (n = 20)
Closest historical parallels
FY2021 NDAA (2020)
Alike: Lame-duck session, sharp partisan conflict, a presidential demand unrelated to defense policy.
Outcome: Vetoed in December and enacted over the veto on January 1, 2021, one day too late for a question like this one.
Where it breaks: Both chambers had already passed strong bipartisan bills; the obstacle was the President, not a Senate blockade.
FY2026 NDAA (2025)
Alike: Same Congress, same committee leaders, no formal conference.
Outcome: Final Senate vote 77 to 20 on December 17 and signed December 18, 2025.
Where it breaks: The Senate had passed its own bill in October 2025. There was no war-related boycott.
FY2013 NDAA (2012)
Alike: Post-election lame duck crowded by a fiscal fight (the fiscal cliff).
Outcome: Passed in late December and signed January 2, 2013.
Where it breaks: The delay was about timing and a signing statement, not a policy blockade.
How it could play out
Every path we see, sized by probability. Paths that resolve YES add up to our 75%.
- Leaders' compromise text passes both chambers in December and is signed by December 31 Yes60%
Committee leaders negotiate a final bill after the election, dropping the SAVE Act and adding some Iran war reporting language.
- Bill punted to the new Congress No17%
An incoming Democratic majority prefers to write the bill in 2027, or the war funding fight swallows the lame duck.
- Senate reconsiders cloture, passes S. 4784, and a conference bill is signed by December 31 Yes15%
Democrats relent after a deal on war oversight or the topline.
- Congress finishes in late December but enactment lands in January No8%
A veto threat, a late signature or an override pushes the law past New Year's Day.
What would change our number
Wicker, Reed, Rogers and Smith announce a compromise text after the election
+12 pointsSenate Democrats publicly tie their NDAA votes to a war powers or Iran withdrawal condition
-10 pointsHouse leaders insist on keeping the SAVE Act in the final bill
-8 pointsThe White House threatens a veto over any provision
-7 pointsTPG 75% vs Kalshi 85%
Kalshi's 'When will the FY2027 NDAA become law? Before Jan 1, 2027' traded between 84 and 87 cents. We are 10 points lower because the market seems to price the 65-year streak without fully weighting the January slip risk; the streak counts fiscal years, not calendar deadlines, and four of the last 20 bills missed December 31.
Market price recorded September 26, 2026 from Kalshi. Analysis, not investment advice.
How this question resolves
Resolves YES if, by 11:59 p.m. Eastern on December 31, 2026, the National Defense Authorization Act for Fiscal Year 2027 (H.R. 8800, S. 4784, or any other bill designated as or substantively serving as the FY2027 NDAA) is signed into law or enacted over a veto. Resolves NO if it is enacted on or after January 1, 2027, or not at all.
Closes: December 31, 2026. Judged by: Congress.gov public law listing and White House signing announcements
Questions people ask
Will the NDAA pass in 2026?
+
Probably. TPG estimates a 75 percent chance the fiscal 2027 National Defense Authorization Act becomes law by December 31, 2026. Congress has enacted an NDAA 65 years running, usually in December. The risk is a slip into January: Senate Democrats blocked the bill 50 to 46 in July over the Iran war, and it has not moved since.
Why did Senate Democrats block the NDAA?
+
On July 14, 2026 the Senate failed 50 to 46 to begin debate on the fiscal 2027 NDAA. Democrats cited President Trump's handling of the war with Iran and the size of the budget, which Sen. Tammy Duckworth called $1.14 trillion, the largest defense budget ever proposed.
What is in the 2027 NDAA?
+
The House version authorizes $1.15 trillion and the Senate committee version about $1.14 trillion. The Senate bill includes a 3.6% troop pay raise. The House bill adds provisions on firearms on bases, military right to repair, a Defense Production Act extension and the SAVE Act voter eligibility measure.
Has Congress ever failed to pass the NDAA?
+
No. The FY2026 NDAA, signed December 18, 2025, was the 65th consecutive year an NDAA was enacted. Some have arrived late, though: the FY2021 bill became law on January 1, 2021 after a veto override, and the FY2013 bill was signed January 2, 2013.
Sources
Every source is dated on or before the September 26, 2026 evidence cutoff. Nothing published later was used.
- [1]FY 2026 NDAA: The Substantial Impact Of The Fiscal Year 2026 National Defense Authorization Act On Federal Procurement Law. Greenberg Traurig, Feb 1, 2026.
“eight of the last 10 NDAAs were enacted in December and the FY 2021 NDAA, Pub. L. No. 116-283, was not enacted until January 1, 2021.”
- [2]FY2027 NDAA: Status of Legislative Activity (IN12704). Congressional Research Service via EveryCRSReport, Sep 1, 2026.
“On July 14, cloture failed (50-46) on the motion to proceed”
- [3]House passes 2027 NDAA while measure remains stalled in the Senate. Breaking Defense, Jul 22, 2026.
“the House passed its version of a $1.15 trillion fiscal 2027 defense authorization bill on a 216-to-212 vote”
- [4]Senate Democrats block must-pass defense policy bill over Iran war objections. CBS News, Jul 14, 2026.
“He also touted the bill's 3.6% pay raise for troops”
- [5]Defense Funding and Policies Set for Next Year as FY2026 NDAA Becomes Law. Morgan Lewis, Dec 19, 2025.
“on December 17 (77-20), sending the 2026 NDAA to the president to be signed into law.”
- [6]NDAA Faces Uphill Battle in Congress as Lawmakers Urge Trump's Restraint on 'Illegal' Iran War. Military.com, Jul 14, 2026.
“The Senate cannot authorize $1.14 trillion in defense spending”
- [7]FY 2026 NDAA: The Substantial Impact Of The Fiscal Year 2026 National Defense Authorization Act On Federal Procurement Law. Greenberg Traurig, Feb 1, 2026.
“becoming the 65th consecutive fiscal year that an NDAA has been enacted”
Version history and integrity
Published forecasts are never edited. When the evidence changes we publish a new version beside the old one, each locked with a sha256 hash of its full contents. When this question resolves it is scored in public on our track record.
| Version | Cutoff | Forecast | Lock hash |
|---|---|---|---|
| v1 | Sep 26, 2026 | 75% Likely | da61d8caefbfea2b4202f0fc807e4db98df7a714491625dfefb354c68f317bdf |
Download every forecast: JSON or CSV (CC BY 4.0). Public sources only. Analysis, not investment or legal advice.
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