I am sure that PhD has taken into consideration that £1,000,000 actually nets down to £542,196 after tax and NI.
Plus I am sure she is fully aware of the implication of payment on account and cash flow requirements.
I am 100% certain she is aware of the 60% taxation anomoly above £100k of Net Adjusted earnings.
And I can also assume that she would let her clients know the implications of taper relief on their pension contributions.