Post-quantum migration: what the UK's 2028, 2031 and 2035 targets mean

By the Vrulum team

Sources checked: 23 October 2026.

The UK's post-quantum migration dates describe work that organisations are advised to plan and complete. They are not predictions that a quantum computer able to break today's public key cryptography will arrive in a particular year.

This article covers the target dates published by the National Cyber Security Centre (NCSC) and some questions for reading claims about progress. It does not audit a named service, forecast when existing cryptography will be broken or give advice for any specific organisation.

The three target dates

The NCSC's guidance, Timelines for migration to post-quantum cryptography (published 20 March 2025, version 1.0), sets out these key milestones:

Target	Activities the NCSC lists
By 2028	Define migration goals, carry out a full discovery exercise and build an initial migration plan
By 2031	Carry out early, highest-priority migration activities and refine the plan into a roadmap for completing migration
By 2035	Complete migration to post-quantum cryptography of all systems, services and products

The NCSC describes these as "indicative timelines" and "target dates" in guidance. The page does not present them as legal requirements. It says the core timelines are relevant to all organisations, but that the guidance is primarily aimed at large organisations, operators of critical national infrastructure and companies with bespoke IT.

The NCSC also says that "there will be a small set of more rarely used technologies for which migration by 2035 may be more difficult", while all organisations should work towards the key dates. It bases the 2035 date on its view that 10 years is enough time for standards, products and widespread uptake to develop.

The targets describe what the NCSC recommends. They do not show that any organisation has begun, met or will meet them.

A finished standard is one milestone

On 13 August 2024, NIST released its first three finalised post-quantum encryption standards. FIPS 203 specifies a key-encapsulation mechanism for general encryption. FIPS 204 and FIPS 205 cover digital signatures, with FIPS 205 intended as a backup method. NIST says the standards are designed to withstand cyberattacks from a quantum computer.

In our view, a standard's publication is evidence that the standard exists. It is not evidence that a particular browser, industrial controller, identity service or supplier product has implemented it correctly. Progress reports are clearer when they record implementation separately.

Reading a discovery claim

The following are our own questions, not findings about any organisation. When an organisation says it has assessed its exposure, it helps to ask what the assessment covers: services, responsible teams, important data, supplier dependencies and long-lived equipment. It also helps to ask what has not yet been examined.

An announcement that a working group exists is a different result from a reviewed migration plan. A useful plan shows which systems are included, who owns the actions and which dependencies could delay delivery. The word "preparing" on its own does not describe measurable progress.

Supplier updates and bespoke systems

In its news release of 20 March 2025, the NCSC says that for many small and medium-sized businesses and organisations, migration "will be routine, as service and technology providers will deliver it as part of their normal upgrades". It adds that "for some larger organisations, PQC will require planning and significant investment". The guidance page notes that where small organisations use custom or specialised software, PQC-compatible updates or replacements should follow the same timetable as for larger organisations.

In our view, a published roadmap, a released feature and a completed deployment are three different things. A feature being available somewhere in a product range does not establish that a particular contracted service or configuration uses it.

For systems an organisation runs itself, relevant evidence includes an agreed migration method, compatibility checks, deployment ownership and recovery arrangements. Technical choices belong with appropriately qualified teams. This article is not a configuration guide.

Quantum key distribution is a different approach

The NCSC paper Quantum networking technologies (published 5 August 2025) updates its earlier white papers on quantum key distribution (QKD). It says that QKD does not provide authentication, so it must be combined with other cryptographic services. It also says the NCSC will not support the use of QKD for government or military applications, and that "PQC is the best mitigation to the threat to cryptography from quantum computers."

It follows that a demonstration of a quantum optical link is not the same as progress against the NCSC's post-quantum cryptography timelines. The useful question is which service and which cryptographic function a claimed change addresses.

Evidence for a completed upgrade

For a named deployment, a useful report would identify the affected service, versions, scope, testing and operating status, along with what is still outside the boundary. One upgraded connection does not show that an organisation's whole estate has changed.

A supplier's statement is different from independently reviewed evidence. Words such as certified, audited or quantum-proof need a record that supports that exact statement and scope.

For most people, the practical step is to keep devices and software on supported security updates. A calendar target is not a reason to buy an unexplained security product.

What would change this assessment

Relevant signals include revised NCSC guidance, new or corrected standards, supported implementations and documented migrations of identified services. We will report each with its date and scope.

The targets are useful markers for tracking those changes. They are not a countdown to a quantum attack, a measure of how much of the internet is already protected or evidence that every migration follows the same path.