Your rights at work depend on your employment status. Employees have the best protectection. Workers (such as agency workers) have fewer rights, for example, they don’t have the right to bring a claim for unfair dismissal. Self employed people have the least protection, but many prefer being self employed as it fits in with their lifestyle or the kind of work they do. However some employers try and label people as self employed to avoid giving people rights.
The way you pay tax and National Insurance will also depend on your employment status. You can get more information about paying tax and National Insurance from TaxAid
For many people it is obvious whether they are an employee, self employed or a worker. However there are grey areas, and the label you are given may not be accurate. For example your employer may call you a casual worker but in reality you are an employee. There is no single conclusive test to determine someone’s employment status, so a tribunal (or HMRC) will apply a “multiple test”. Some of the things they will look at are if your employer has an obligation to give you work (or pay you even if there is no work), if you personally have to turn up and do the work, rather than sending someone else and if your employer has control over when, where and how you do the work.
If there is a dispute about your employment status, it will either be to do with your tax and National Insurance affairs, or a statutory payment such as Statutory Sick Pay, in which case HMRC decide; or because you are making a complaint to an employment tribunal, in which case the tribunal would decide.
If your employment status is not clear, or you are in disagreement with your employer about it, you can find more information on the Direct gov website or seek advice from, for example, a Citizens Advice Bureau.