Good explanation slackboy. I guess the op didn’t realise he’d be liable for the employer’s NI contribution. But if he’d been told he wouldn’t he’s got a reasonable claim. Proving the claim is another thing.
But this whole umbrella stuff is massively wrong, vunerable workers having to pay employee and employers NI should be called out for the racket it is and made illegal.

Agreeing with everyone else, you need to show why you thought you’d be being taken on as an employee at the higher rate, if that’s your argument. If the agency advertised an employee position at a salary then it’s different to advertising an hourly rate and separately advertising an umbrella option. But like everyone else I’m not comfortable.

If you have been working 50 hour weeks for over 9 months for the same client then, in my book, you look a lot like an employee of that client and should be entitled to employment rights like any other employee (sick pay, pension) and of course the employer would be liable for the employer’s NI. But this is a massively complex area with a large and growing body of case law which I don’t understand. And the client isn’t your respondent anyway.

I doubt you’d win a tribunal based on the evidence.

Is it unfair? Yes.

Have they breached their contract with you? Unlikely.

You’ve basically been suckered, but you did accept the original contract terms and continued working there for 9 months on those terms. The fact that those terms and the employment arrangement led to you recieving less than you expected isn’t really something the tribunal can remedy.

The OP only worked there for 10 weeks it’s a lot of stress and hassle for something that’s not going to stand, I’m amazed it has got this far.

It’s a lot of stress and hassle for something that’s not going to stand

Quite.

I get the, “but I thought” part, and it really sucks being pissed about on money, but here is Quest’s PAYE Employment Contract:

https://www.quest-pay.co.uk/wp-content/uploads/2018/05/Quest-Pay-PAYE-Employment-Contract.pdf

6.5. The Company shall be entitled to make the necessary legal deductions from the
Remuneration for both the Employee and the Company as required by UK and/or
foreign tax and social security authorities

2.10. In the event the Employee commences the Services without signing the Agreement
then the Employee will be deemed to have accepted the terms of this Agreement.

5. Warranty
The Employee warrants that he:
5.1. has read and understood this Agreement, and

deleted – i went off on a tangent about umbrella companies

If the OP thought that he/she was working for the agency and not Quest then Quest’s terms aren’t really relevant. You can’t arbitrarily contract with someone without their knowledge (with the notable exception of car parking). Although you’d have thought that a payslip would have raised alarm bells. Perhaps it did. Remember the OP’s case is against the agency not Quest.

as skids says,’ he hourly rate I was ‘paid’ had dedcutions for their NI contributions and my holiday pay which they had to save up so I could be paid for holidays!’, but they said they had already paid holidays
I think the basis is firly obvious- I was promised £10.50 PAYE, was paid much less, , and I want my £1000

alric – as someone else has said if we who want to help cannot understand your case then I think you will really struggle to get a result at tribunal.

From what info you have given us it looks to me like you did get a gross of £10.50 an hour – its just the deductions are more than you expected.

If you really want to win at tribunal you are going to have to get your argument much clearer

In the same circumstances I would also ‘…want my £1,000’ but would also be acutely aware that, as a matter of fact, costs can be awarded at an employment tribunal; it’s not the norm but the possibility should not be discounted.
Do you have legal representation? For ‘only’ £1,000 I would be surprised and would think any honest solicitor would tell you the downside doesn’t justify the cost or effort.
As you appear to be intent on pursuing this you would be better off using your time to fully prepare your case – facts and whether or not the other party breached employment law are the only things that matter.
The broad consensus of replies is that you should forget it.
Tell us how it all works out.

You’re an employee of the umbrella company as well, so the end client/agency can tell you whatever they want they don’t directly employ you, the contract to the agency and in turn to the umbrella, its your written agreement with the umbrella company that matters.

Is it them you are taking to tribunal as they are your employeer in this instance?

Acas helpline offers free advice: https://www.gov.uk/pay-and-work-rights

Best of luck.

Thanks for all the help
A year later,with just the help of ACAS,I am no longer out of pocket(bar the hassle of pursuing these lowlife), and It didnt get to the Industrial Tribunal

Good news.