Preferred supplier/rate transparency question

[Wanderer]

I have been offered a contract at a city financial firm through a preferred supplier. They say that they need to negotiate a rate and seem to be talking around 1.5 times what I grossed in salary + bonus as a PAYE employee last year.

Welcome!

That sounds about right. See item 13 in this post. When you do the calculations, don't overestimate how much you will make in a year (will your contract even run for that long!). Base it on 200-210 working days per year to cover things like unemployment, sickness, holidays, training etc.

Do I have any guarantee that this is what was negotiated with the firm I will be writing software for and that the preferred supplier is not creaming any extra off the top?

No you don't.

In fact, the supplier will definitely be creaming some off the top, exactly how much is uncertain. I've seen preferred suppliers take about 5% of the day rate but I've also seen another supplier at the same client taking 40%! There isn't much you can do about it unless the client is willing to discuss your rate directly with you (some are, some aren't) or if you can somehow find out how much the supplier is getting paid by the client.

[TheDude]

Apologies if I missed this in the FAQs.

I have been offered a contract at a city financial firm through a preferred supplier. They say that they need to negotiate a rate and seem to be talking around 1.5 times what I grossed in salary + bonus as a PAYE employee last year.

Do I have any guarantee that this is what was negotiated with the firm I will be writing software for and that the preferred supplier is not creaming any extra off the top?

Cheers.