How the Off-Payroll Rules Changed in April 2021

How the off-payroll rules changed in April 2021 for the private sector

The off-payroll working rules, commonly known as IR35, changed significantly for the private sector on 6 April 2021. This IR35 reform shifted a key administrative responsibility away from contractors' own limited companies and onto the businesses that engage them. If you contract through a personal service company, understanding this change is essential background, even though it does not tell you what your own status is.

This article explains what changed, who it applies to, and where to find the primary HMRC guidance. It is educational only: for a view on any specific engagement, you will need a qualified IR35 contract reviewer or accountant.

What actually changed in April 2021

Before 6 April 2021, private and voluntary sector clients were not responsible for considering whether the off-payroll rules applied to a contractor's engagement. That responsibility sat with the contractor's own intermediary, typically their limited company.

From 6 April 2021, that responsibility moved. HMRC's guidance confirms that for engagements through personal service companies or other intermediaries, medium and large private-sector clients became responsible for determining status themselves and for issuing a Status Determination Statement (SDS). This mirrored the approach already used in the public sector since 2017.

In practice, this means the end client, not the contractor's own company, now decides whether a particular engagement falls "inside" or "outside" the off-payroll rules, and must communicate that decision, along with reasons, to the contractor and the agency in the supply chain.

Which clients does the reform apply to?

The April 2021 reform did not apply to every organisation. HMRC guidance is clear that small private-sector clients fell outside the reform: where a client qualifies as "small" under company law tests, the previous position continues to apply, meaning the contractor's own intermediary remains responsible for assessing status.

Medium and large private-sector organisations, on the other hand, became responsible for status determinations. HMRC's client guidance explains that company size is measured using the size tests set out in company law, generally based on factors such as turnover, balance sheet total, and number of employees. Contractors working with smaller businesses may therefore find the off-payroll landscape looks quite different from those working with larger organisations, which is worth checking before assuming how a particular engagement will be handled.

Why the reform happened

The government's stated aim, as set out in its update on the impacts of the 2021 reform, was to address perceived low compliance with the existing IR35 rules by moving the compliance burden to the party with more resources: the engaging organisation. The 2017 public-sector reform and the 2021 private-sector reform are described together as administrative changes that shifted responsibility for operating the rules from the worker's intermediary to the client, except where the client is small and outside the public sector.

It is worth noting the reform changed who is responsible for determining and communicating status, and for operating PAYE where a role is inside the rules. It did not change the underlying tests used to work out whether someone is genuinely self-employed for tax purposes. Those tests still focus on matters such as the right of substitution, the degree of control the client exercises over how, when and where work is done, and the broader picture of the working relationship, reflecting principles considered in case law including PGMOL.

The Status Determination Statement

Since the reform, medium and large clients must produce an SDS for each engagement caught by the rules. HMRC's guidance on understanding off-payroll working sets out what this involves and confirms the rules changed from 6 April 2021, having originally been due earlier before a delay was announced.

An SDS is evidence provided by the client setting out their conclusion and reasoning. It is not proof of status in itself, and CEST results, where a client uses HMRC's Check Employment Status for Tax tool, are described by HMRC as not determinative. Contractors who disagree with an SDS can raise this through the client-led status disagreement process referenced in HMRC's guidance, though outcomes will depend on the facts of the engagement.

What this means for contractors today

For contractors searching for work, the practical effect is that many private-sector clients now issue their own status decisions before or alongside a contract offer. When a listing states that a role is "outside IR35", this is the client's assessment, not a guarantee, and not something this platform verifies or confirms.

If employment rights concerns arise around a contracting arrangement, these sit separately from tax status and are the remit of the Fair Work Agency, not HMRC.

Contractors reviewing new opportunities may find it useful to browse outside-IR35 contracts currently listed, or to check day-rate benchmarks to see how rates compare across sectors and determinations.

This platform does not determine, verify, or warrant IR35 status; the SDS is the client's legal responsibility. Contractors should take their own advice and consider IR35 insurance.