New Hampshire's 2024 Code Deadline: What Changes January 1

New Hampshire's State Building Code moved to the 2024 International Code editions on July 1, 2026, and a six-month concurrence period lets an applicant elect either the 2021 or the 2024 editions through December 31, 2026. From January 1, 2027, every permit request in the state must follow the 2024 editions. The election is made per permit application, and RSA 155-A:2 does not let a job mix the two.

TL;DR

• The 2024 editions become mandatory for all New Hampshire permit requests on January 1, 2027.
• The concurrence window closes December 31, 2026, and the election sits on the application.
• RSA 155-A:2 forbids combining the two editions on one submission.
• The energy code stayed at 2018 and electrical stayed at the 2023 NEC.

What actually changes in New Hampshire on January 1, 2027?

The list of adopted model codes changes, and the applicant's choice disappears.

The New Hampshire Building Code Amendments were reviewed and approved by the Building Code Review Board through May 8, 2026, ratified by the General Court under HB 1059 of 2026, and took effect July 1, 2026. Six model codes moved forward one cycle: the International Building Code, the International Residential Code, the International Existing Building Code, the International Plumbing Code, the International Mechanical Code and the International Swimming Pool and Spa Code, each carrying New Hampshire amendments.

Two did not move. That distinction is the whole practical story, and almost nobody selling into New Hampshire construction has it straight.

Right now a New Hampshire applicant has a choice. In January the choice is gone. Nothing about the physical work changes on New Year's Day. What changes is which edition the paperwork has to answer to.

Why is December 31 a filing deadline, not a construction deadline?

Because the statute attaches the election to the application, not to the job.

RSA 155-A:2 establishes a concurrency period "for a period of 6 months after the effective date of the code adopted under RSA 155-A:1, IV." Inside that window, building permits and other required documents may, at the election of the applicant, show compliance using either the code in effect just before the new adoption or the newly adopted code. Then comes the clause most summaries skip: "but not a combination of the 2 codes."

Read that twice. It means two things at once.

First, the deadline is a counter date. A set of drawings prepared against the 2021 International Residential Code stops being a filing option on December 31, 2026, whatever the intended start date was. Plans sitting on a designer's desk in November are an asset with an expiry.

Second, the election is all or nothing per submission. A designer cannot cherry-pick the 2021 provisions that suit one part of a project and the 2024 provisions that suit another. That forecloses the obvious workaround, and it makes the elected edition a durable, knowable fact about every job now in the queue.

For anyone whose work sits downstream of a drawn set, that is a conversation with a date on it.

Which codes moved, and which did not?

Six moved to 2024. Two stayed where they were. Here is the split, with our own New Hampshire filing volume for the twelve months to August 21, 2026 where the mapping is clean.

Code	Edition from July 1, 2026	Who reads it	NH permits, 12 months
International Building Code	2024	Commercial and multifamily builders	see building, below
International Residential Code	2024	One- and two-family builders, additions, decks	see building, below
International Existing Building Code	2024	Renovation and alteration contractors	see building, below
International Plumbing Code	2024	Plumbers	758 plumbing
International Mechanical Code	2024	HVAC contractors	712 mechanical
International Swimming Pool and Spa Code	2024	Pool and spa builders	folded into building
International Energy Conservation Code	2018, unchanged	Insulation, window, envelope trades	folded into building
National Electrical Code (NFPA 70)	2023, unchanged	Electricians	637 electrical

One honest caveat on that right-hand column. Our New Hampshire file records 4,642 building permits over the same twelve months, and it does not separate residential from commercial or split out pool work, so those rows share a single bucket rather than each owning a number.

The two bold rows are where the money is. If you sell insulation, windows, air sealing or electrical work in New Hampshire, January 1 changes nothing for your scope, and telling a nervous customer that plainly beats joining the general noise. If you sell plumbing or HVAC, your governing code did move, and the 758 plumbing and 712 mechanical permits in our file are the population that has to care.

How do you find the jobs sitting inside the concurrence window?

Filter on application date, because that is the field the statute keys to.

Between July 1 and August 21, 2026, our New Hampshire file recorded 1,074 permit applications across Concord, Hampton, Exeter and Seabrook. Every one of them was filed inside the concurrence window and carries an edition election. Of those, 412 name a contractor, a little under two in five, which is normal for New Hampshire rather than a defect in the feed.

The distribution is lopsided in a way worth planning around. Of the 1,074, some 726 are building permits, with 98 mechanical, 97 electrical and 70 plumbing behind them. Trade permits are scarce here not because the trades are idle but because most New Hampshire towns never publish them separately, a pattern we worked through in how New Hampshire permit records change from town to town.

Two practical filters follow.

For plumbing and HVAC, pull applications from July 1 onward and treat every one as a job whose plumbing or mechanical code election is already fixed. For everyone downstream of a design, the useful cut is the reverse: building permits filed in the last sixty days whose contractor field is blank. Those are jobs with an owner, a scope and no committed trade, and New Hampshire is the one state where a blank contractor field is genuinely common rather than suspicious, for reasons we covered in why New Hampshire has no general contractor licence.

When should you reach out, and how do you read a December spike?

Weeks 1 through 4 after the application date, with more urgency than usual between now and New Year.

The timing logic is the ordinary one. A permit is a signal about the homeowner, not the contractor, and the four weeks after filing are when the follow-on trades get chosen. Working the application date rather than waiting for a decision is the same discipline behind speed-to-lead outreach on permit data.

What is unusual is what sits on the other side of the deadline. New Hampshire's seasonal trough is severe. Our file runs roughly 750 to 780 permits a month across April, May and June, and falls to roughly 405 to 438 in January and February. The mandatory-compliance date lands directly on the softest weeks of the year.

So expect noise, and be careful how you read it.

A worked example from our own data. October 2025 produced 1,003 New Hampshire permits against 681 in September and 461 in November, which looks like a statewide surge. It was not. Concord alone contributed 717 of that October figure against 393 the month before, so a single town moved the entire state line. We cannot tell you what caused it, and we are not going to guess.

The lesson transfers directly. If December 2026 shows a filing spike, check it town by town before you staff against it. In a four-town file, one municipality's recording practice can manufacture a trend that never happened.

What to say in your outreach

Lead with the date and the specific code, not with urgency.

For a plumbing or HVAC contractor writing to a homeowner or builder on a July or August application: "Your permit went in during the concurrence window, so it can still be built to the 2021 International Plumbing Code. That election is locked to the application and it cannot be mixed, so it is worth confirming which edition your plumber priced before the fixtures get ordered."

For an insulation, window or electrical contractor, the strongest message is the one that removes a worry: "The January 1 code change does not touch your scope. New Hampshire kept the energy code at the 2018 International Energy Conservation Code and kept electrical work on the 2023 National Electrical Code, so nothing about this job's specification changes at New Year."

For anyone selling to a designer or an owner with drawings not yet filed, one line does the work. Plans drawn to the 2021 editions are filable until December 31 and unfilable on January 1.

Avoid deadline theatre. New Hampshire operators have watched this before, since the 2021 editions took effect on July 1, 2024 on the same pattern, and a contractor who oversells the cliff loses credibility in a state where everybody knows the building official personally.

How permits.llc fits in

We index New Hampshire permits from Concord, Hampton, Exeter and Seabrook, 12,497 records reaching back to October 2022, with application dates you can filter on directly. That is four towns in two counties, not the whole state, and we would rather you know that up front than discover it after a purchase.

To work the concurrence window yourself, download the New Hampshire permit data and filter to applications dated July 1, 2026 or later. To see what coverage looks like before committing, browse New Hampshire permits by county, or set up permit alerts so new filings reach you inside the four-week window rather than after it.

The December 31 date is real and it is close. The useful version of it is narrower than the panicked version: six codes moved, two did not, the election lives on the application, and no job gets to mix them.