FIRE to IRIS 2026: Specialist US UK Tax Services Guide

The IRS is retiring the Filing Information Returns Electronically (FIRE) system. Under IR-2026-99, the final FIRE submission window closes at 3 p.m. ET on 19 November 2026, and from 1 January 2027 the Information Returns Intake System (IRIS) becomes the only electronic channel. Your FIRE credentials do not migrate. Every affected business needs a new IRIS Application for a Transmitter Control Code before January.

For UK-domiciled companies with US payroll, US contractors, US-source payments or a US subsidiary, this is not a software upgrade. It is a credentialing problem with a hard deadline, an identity-verification requirement that many overseas directors cannot satisfy, and a 45-business-day review queue sitting directly in front of the January information-return season. Specialist US UK tax services exist precisely for this kind of dual-jurisdiction operational risk, and Jungle Tax has been moving client filing infrastructure across since the announcement.

What exactly changes on 19 November 2026?

FIRE has been the IRS workhorse for bulk information returns for decades. It accepts fixed-width ASCII files built to the Publication 1220 specification, it issues its own Transmitter Control Code, and it has been the default route for anyone filing more than a handful of Forms 1099, 1098, 5498, W-2G or 1042-S. It is being decommissioned, and the shutdown is staged rather than instantaneous.

Date	What happens	Practical consequence
1 November 2026	Last day to submit test files through the FIRE Trading Partner Test System	No further validation of legacy ASCII files; your testing must move to IRIS ATS
9 November 2026	Last day to make changes to an existing Information Returns (IR) Application for TCC	Adding or removing a Responsible Official on the legacy application becomes impossible
19 November 2026, 3 p.m. ET	Last day to file information returns through FIRE	Late or corrected prior-year returns must wait for IRIS
From December 2026	Legacy IR Applications move to read-only archival status	Historic records remain visible; the application is no longer actionable
1 January 2027	IRIS becomes the sole electronic filing system	Current year, prior year and corrections all route through IRIS
Late January / March 2027	Tax year 2026 information return deadlines fall due	Zero slack between migration and filing season

Note the gap that most commentary glosses over. Between 19 November 2026 and 1 January 2027 there is a genuine dead zone for FIRE filers. If you discover in early December that a tax year 2025 Form 1099-NEC was omitted, the legacy channel is gone and the replacement is not yet in general service for that filing. Anyone who habitually files corrections late in the calendar year should bring that work forward. The IRS sets out the sequence on its own FIRE system page.

Why does a UK business have US information return obligations at all?

This is the question that stops most UK finance directors from acting, and the assumption behind it is usually wrong. US information reporting attaches to the payment and the payer's status, not to where the company is incorporated. A UK limited company can sit squarely inside the regime in several ordinary commercial situations.

Where a US-connected UK business gets caught

• A US subsidiary or LLC. Any US entity paying US persons for services, rent, royalties, prizes or attorney fees generally reports on the Form 1099 series. The parent's UK domicile is irrelevant.
• A UK company engaged in a US trade or business. Where payments are effectively connected with US activity, reporting obligations can follow even without a separate US entity.
• Withholding agent status. A non-US company that controls, receives, or pays an amount subject to Chapter 3 withholding can be a withholding agent, with Form 1042 and Form 1042-S obligations. This catches UK groups paying US-source royalties, licence fees or dividends far more often than they expect.
• Contractors who work on US soil. When a contractor performs part of the engagement physically in the United States, that portion is generally US-source income, reportable on Form 1042-S, with a statutory 30% withholding rate unless a treaty article reduces it.
• Founder and exit events. Earn-outs, deferred consideration, escrow releases and option settlements paid across a transaction close frequently generate information returns that nobody assigned to an owner during diligence.

Form 1042-S deserves particular emphasis for cross-border groups, because the liability is asymmetric. The recipient does not file it; the withholding agent does. If the withholding agent under-withholds, the IRS looks to the payer for the tax it should have deducted, plus penalties and interest, long after the contractor has been paid and moved on. That exposure does not disappear simply because the filing platform changed.

The tax year 2026 electronic filing threshold

The aggregate electronic filing threshold is low. A business filing ten or more information returns in total across covered form types is generally required to file electronically. That aggregation is the trap: five Forms 1099-NEC, three Forms 1042-S and two Forms 1099-MISC cross the line even though no single form type looks material. Once you are over the threshold, the paper alternative is not available and the IRIS credential becomes mandatory rather than optional.

Your FIRE TCC does not carry over — what is an IRIS Application for TCC?

This is the single most expensive misunderstanding in the transition. A Transmitter Control Code issued for FIRE is not portable. It cannot be re-pointed, converted, or grandfathered. A separate IRIS Application for TCC must be completed through IRS e-Services, and it produces a different code tied to a different system.

The application requires, at minimum: the legal entity name exactly as held in IRS records, the Employer Identification Number, the business structure, the transmission method you intend to use, the form types you will file, and named individuals in defined roles. Ordinarily the IRS expects a minimum of two Responsible Officials, with a limited number of Authorized Delegates permitted; sole proprietorships and single-member LLCs are typically permitted a reduced roster. Every named Responsible Official must be able to sign in and access the application in their own right, which means each of them must independently complete identity verification.

Portal or Application-to-Application?

IRIS offers two routes, and choosing the wrong one costs weeks.

• The IRIS Taxpayer Portal is free and browser-based. It supports manual entry and CSV upload, with a cap of 100 returns per submission. For a UK company issuing a modest volume of Forms 1099 through a US subsidiary, this is usually sufficient and materially simpler.
• Application-to-Application (A2A) is the machine-to-machine channel for higher volumes and third-party or in-house software. It is XML-based, requires schema conformance, and requires Assurance Testing System (ATS) work before production transmission is enabled. ATS cannot begin until the TCC is approved.

The technical shift matters as much as the credential. FIRE consumed fixed-width ASCII built to a positional specification. IRIS consumes structured CSV or XML. Any internally maintained export routine, any legacy mapping in a finance system, and any bespoke script that has quietly produced Publication 1220 files for years will need to be rebuilt and revalidated. That is a development task with a lead time, not a configuration toggle. The IRS overview of the replacement platform is published at IRS.gov: e-file information returns with IRIS.

The obstacle generalist guidance ignores: no SSN and no ITIN

Here is where a UK-headquartered group diverges sharply from a domestic US filer, and where almost every mainstream article on the FIRE retirement simply stops.

The standard IRIS Application for TCC is gated behind IRS e-Services identity proofing. Each Responsible Official must verify their identity through the IRS credential service provider, and that verification is built around a US taxpayer identification number. A British finance director with a UK passport, a UK address, no SSN and no ITIN frequently cannot complete it, even though the company holds a valid US EIN and has genuine, undisputed filing obligations. The credential fails on the human, not on the entity.

The Foreign Filer TCC Registration System

The IRS has provided a dedicated route for exactly this population. A foreign filer, for these purposes, is a foreign person required to file information returns that does not have an authorised user holding an SSN or an ITIN. Where the authorised users cannot obtain or maintain a TCC directly through IRIS, the Foreign Filer TCC Registration System provides an alternative registration pathway.

The route is materially different in shape:

• Establish a secure sign-in account with the IRS credential provider, keeping the email address consistent across every step.
• Create a Foreign Filer TCC account, which issues a Foreign Filer ID.
• Register for a TCC Global Intermediary Identification Number (GIIN), request the TCC, and enrol with the International Data Exchange System (IDES).

Transmission then runs through IDES rather than through the ordinary IRIS channels, covering Forms 1042-S, applicable Forms 1099 and other information returns. The critical eligibility point cuts both ways: if your authorised users do hold US taxpayer identification numbers, you are expected to use standard IRIS and the foreign filer route is not open to you. Groups with a mixed board therefore need to decide deliberately which individuals are named, because that choice determines which registration system applies. Applying down the wrong path and discovering it in December is an expensive error. The eligibility conditions are set out on the IRS Foreign Filer TCC Registration page.

How does this compare with UK filing infrastructure?

UK finance teams instinctively reason by analogy to HMRC, and the analogy misleads them. The two systems are architected on opposite assumptions.

Dimension	United States (IRS / IRIS)	United Kingdom (HMRC)
Core reporting model	Third-party information returns filed annually per payee (1099 series, 1042-S)	Real Time Information under PAYE, filed on or before each payment; CIS monthly returns for construction
Filing credential	Transmitter Control Code, system-specific, non-transferable between FIRE and IRIS	Government Gateway credentials, reusable across most HMRC services
Identity verification	Individual identity proofing tied to a US taxpayer identification number	Gateway enrolment; no requirement for a UK-resident individual identifier of equivalent rigour
Route for overseas officers	Separate Foreign Filer TCC Registration System and IDES transmission	No equivalent separate system; overseas directors generally enrol normally
Contractor reporting	Form 1099-NEC for US persons; Form 1042-S for US-source payments to foreign persons	Generally no annual contractor return outside CIS; off-payroll rules shift status determination to the engager
Approval lead time	Suitability review commonly quoted at up to 45 business days, longer in peak season	Gateway enrolment typically days, activation codes by post
Correction mechanism	Corrected information returns filed through the same electronic platform	Earlier Year Update / amended RTI submission

The operational takeaway is blunt. HMRC credentials are effectively evergreen; a UK team that has never had to re-credential does not carry the institutional memory that this transition demands. HMRC's own baseline guidance on the UK side sits at GOV.UK: PAYE and payroll for employers, and the closest UK analogue to contractor information reporting is described at GOV.UK: what you must do as a CIS contractor. Neither prepares a UK controller for a US credential that expires with its platform.

Why is the 45-day review the real deadline?

Work the calendar backwards, because the November dates are a distraction from the binding constraint.

The IRIS application is not a registration form; it triggers a suitability review. The IRS validates entity identity, checks the filing and payment compliance history of the business, and reviews the named Responsible Officials. Guidance commonly cites up to 45 business days, and the queue lengthens materially between October and January when every remaining FIRE filer arrives at once. ATS testing for A2A filers cannot start until approval lands.

An application submitted in late October 2026 can therefore easily resolve in January 2027, after the recipient statement deadline has already passed. An application submitted in September resolves comfortably. That difference is the entire risk, and it is a scheduling problem rather than a technical one.

A second, less obvious risk sits inside the suitability review itself. Because the IRS examines the filing and payment compliance history of the entity and its officials, a group with unresolved US exposure, unfiled returns, or an outstanding balance may find the review surfaces problems the board did not know it had. Where that is a live possibility, the sequencing question belongs with US UK tax accountants before the application is filed, not after a rejection. Groups already remediating historic non-compliance should coordinate the credential work with their disclosure strategy; our IRS streamlined filing team routinely runs both workstreams in parallel so that neither prejudices the other.

What does non-compliance actually cost?

Information return penalties are assessed per return and tiered by lateness, and they apply twice over: once for the return filed with the IRS and again for the payee statement. Because the penalty is per form, a company with a few hundred payees converts a credentialing oversight into a six-figure exposure with startling speed. Intentional disregard carries a substantially higher per-return penalty with no annual cap.

Critically, "we could not obtain a TCC in time" is not a strong reasonable-cause position when the retirement was announced with more than a year of notice and published deadlines. The IRS position is that filers had ample warning. A UK group planning to argue reasonable cause should assume it will need contemporaneous evidence of timely application and a genuine, documented external obstacle.

A practical migration plan for a US-connected UK business

Immediately (by end of September 2026)

• Inventory every information return type your group filed for tax years 2024 and 2025, across every entity and every EIN. Include forms filed by a US subsidiary, by an outsourced payroll provider, and by any third-party transmitter.
• Confirm whether each EIN's legal name matches IRS records exactly. Mismatches are a common cause of application rejection and take weeks to resolve separately.
• Determine, for each candidate Responsible Official, whether they hold an SSN or ITIN. This single fact decides whether you use standard IRIS or the Foreign Filer route.
• Decide portal versus A2A on projected volume, not on habit.

October to mid-November 2026

• Submit the IRIS Application for TCC, or begin the Foreign Filer registration sequence, and record the submission date.
• Complete identity verification for every named official. Do not assume a colleague will complete it; chase it to confirmation.
• Bring forward any outstanding prior-year corrections and file them through FIRE before 3 p.m. ET on 19 November 2026.
• Make any final changes to the legacy IR Application before 9 November 2026.

December 2026 to January 2027

• Rebuild and validate data exports against the IRIS CSV or XML specification. Complete ATS testing if filing via A2A.
• Re-verify payee data quality: taxpayer identification numbers, name-TIN matching, addresses, and treaty documentation supporting any reduced withholding rate on Forms 1042-S.
• Confirm state-level filing obligations separately. Not every state participates in combined federal-state filing, and the federal platform change does not resolve state requirements.
• Verify recipient statement delivery arrangements, which are a separate obligation from the IRS filing.

Where this intersects with wider cross-border position

For founders and business owners, the information-return question rarely arrives alone. A UK company that discovers it should have been filing Forms 1042-S usually discovers simultaneously that withholding was not operated, that treaty documentation was never collected from payees, and occasionally that the US entity itself has an unfiled return history. Handled properly, the credential migration is the moment to review the whole position rather than patch one platform. Our US tax services and UK tax services teams work the two sides together, and further technical material is collected in our guides library.

The judgement call most boards get wrong

Many UK groups will conclude that because a third-party provider transmits their returns, the transition is somebody else's problem. Sometimes that is correct. But it is only correct if the provider transmits under its own TCC and has confirmed in writing that it has completed its own IRIS migration. If your group holds its own TCC, or if the provider merely prepares files that you transmit, the obligation is yours. The distinction is worth confirming in writing this month, because the two positions look identical from inside a finance function until January, when only one of them files successfully.

Equally, a group that has always filed a small volume on paper should re-check the aggregate threshold before assuming nothing changes. Business growth, a new US subsidiary, or a single transaction year with multiple earn-out payments can push a previously exempt filer over the electronic filing line in the same year the platform changes.

Speak to us before the November window closes

The FIRE retirement is a rare example of a compliance change where the cost of acting early is trivial and the cost of acting late is severe and unarguable. If your group has US payees, a US subsidiary, US-source payments, or an exit event that generated information returns, the sensible step is a short, confidential review of which entities need which credential, who can complete identity verification, and whether the Foreign Filer route applies to your board. Please contact our cross-border team to arrange a confidential consultation while there is still room in the IRS review queue.