What is a statutory excuse, and why does it matter?
A statutory excuse is your defence against liability for a civil penalty. The Home Office employer's guide defines it as "an employer's defence against liability for a civil penalty, which can be obtained where the prescribed right to work checks have been carried out." You get it by doing the prescribed check correctly before employment starts, then keeping the right evidence.
Note the precise language. It's a statutory excuse, not a "legal defence" or "immunity" in the everyday sense. It protects you from the civil penalty for that worker, provided you followed the rules and the worker turned out to lack permission. It does not license you to employ someone you know has no right to work, and it does not shield you from criminal liability if you knowingly do so.
The practical point is what the excuse is worth. The Code of Practice that came into force on 13 February 2024 sets the civil penalty at up to £45,000 per illegal worker for a first breach and up to £60,000 per illegal worker for a repeat breach within three years. A correct check, retained properly, is what stands between your organisation and those figures.
What is the difference between List A and List B documents?
List A and List B split documents by how long the person's right to work lasts. The employer's guide is explicit: List A "contains the range of documents you may accept for a person who has a continuous right to work in the UK," and a correct check gives "a continuous statutory excuse for the duration of that person's employment with you. You do not have to conduct any follow-up checks on this individual."
List B is the time-limited side. The guide states it "contains a range of documents you may accept for a person who has a temporary right to work in the UK," and a correct check establishes "a time-limited statutory excuse. You will be required to conduct a follow-up check in order to retain your statutory excuse."
So the list a document falls into tells you whether you are finished or whether you have just started a clock. List A means you check once, keep the evidence, and stop. List B means you check now, diarise the follow-up, and check again before the deadline. Mistake a List B holder for a List A holder and you will skip a follow-up you were legally required to do.
| Feature | List A | List B |
|---|---|---|
| Right to work | Continuous / permanent | Temporary / time-limited |
| Statutory excuse | Continuous, lasts the whole of employment | Time-limited, ends with their permission |
| Follow-up check | Not required | Required to retain the excuse |
| When to re-check | Never (for this purpose) | On or before the date permission ends |
When do you need to do a follow-up check?
You need a follow-up only for List B holders, and the timing is fixed by when their permission runs out. The employer's guide says a follow-up check "should take place on, or before, the date their permission comes to an end." Do it after that date and there is a gap where you held no valid statutory excuse.
Take a fully hypothetical example. A care home employs a senior carer whose visa permits work until 30 September. That is a List B situation, so the excuse is time-limited. The home runs a fresh right-to-work check on or before 30 September, confirms the carer's permission has been extended, and keeps the new evidence. The excuse continues. Miss that date, and from 1 October the home is exposed even though nothing about the carer changed.
A follow-up is not always a tidy renewal, and that is worth being honest about. The re-check might show the person's permission has ended and not been extended, in which case continuing to employ them is exactly the risk the check exists to catch. The job is to never let the date pass unchecked. An expired List B excuse gives you no warning of its own. You only find out when a Home Office visit forces the question.
What are the three valid ways to check right to work?
There are three lawful methods, and which one fits depends on the worker's status and documents.
The first is a manual document check. You inspect the person's original documents in their presence (or on a live video call while holding the originals), confirm they are genuine and belong to the holder, and keep clear copies with the date. This is the route for people whose acceptable documents cannot be verified online, including British and Irish citizens using a passport.
The second is Identity Document Validation Technology (IDVT) through a certified Identity Service Provider (IDSP). An IDSP uses IDVT to verify a digital copy of a physical document and confirm the holder is its rightful owner. Since 6 April 2022, employers have been able to use an IDSP to complete the digital identity check for British and Irish citizens who hold a valid passport (including Irish passport cards), which provides a continuous statutory excuse.
The third is the Home Office online right to work check, done with a share code the worker generates plus their date of birth. This is how you check most people who are not British or Irish citizens. Worth knowing: British and Irish citizens cannot get an online share code, so for them you use the manual check or an IDSP, not the online service.
How do you avoid a civil penalty across both lists?
Treat List A and List B as two different jobs. List A is a record-keeping job: run the prescribed check correctly before the person starts, keep dated copies of the evidence, and you hold a continuous statutory excuse for their whole employment. There is nothing further to do for right-to-work purposes.
List B is a deadline-management job. You run the same kind of check up front, but the excuse expires with the worker's permission, so the work is making sure the follow-up happens on or before that date. One missed date per worker is one potential penalty. The Code of Practice sets the starting point at up to £45,000 for a first breach and up to £60,000 for a repeat breach within three years, calculated per worker, so the cost scales with the number of people whose follow-ups slip.
My view, grounded in those figures: the expensive failure is rarely the initial check. It is the forgotten List B follow-up months later. Initial checks get attention because they are tied to onboarding. Follow-ups have no natural trigger. They sit on a future date that nobody owns unless someone builds a reminder, and that is the gap most worth closing.