Is Employer NI a way for Umbrella companies to pass on HMRC fines to contractors?

Employer’s NI is calculated at 15.05% on earnings above £175 per week, and whoever establishes themselves as your employer is legally obliged to pay this to HMRC.
Although you work on the assignment through your agency, they aren’t your employer. You’re employed with Danbro on an overarching contract of employment. As the agency doesn’t have the administration and associated cost of employing you as if you were a PAYE employee, the contracted rate you’re offered will take this into account and will be uplifted to allow for the necessary employment costs.
Each week (or month) we will send an invoice on your behalf charging your agency for the work carried out. Once payment is received we will make the statutory deductions relating to your employment, we’ll retain our agreed margin, and we will pay you your take-home pay.
All of this will be clearly outlined on your payslip, which can be viewed online. Some Umbrella companies may not be upfront but at Danbro we always aim to be transparent. No hidden fees or deductions.