Taxation of Non Savings Income – ACCA Taxation TX-UK lectures

I’m looking at the last question in regards to the below video for Taxation of Non Savings Income – ACCA Taxation TX-UK lectures. Link is below for ease of reference.

https://www.youtube.com/watch?v=98bNjk99ypg

I just wanted to clarify something, what figure is it that you used to determine whether Kerry was a higher rate tax payer ?

Is it always the total taxable income figure rather than the net income? So the amount after the personal allowance is deducted, in this case the £92430 figure ? which is More than £37,700 therefore making them a higher rate tax payer.

Or is it the figure for the adjusted net income = Net income -Gift Aid = £99,000

or is it just simply the net income ( £105,000) – Total income less qualifying interest?

Getting slightly confused here on which figure should be used as the basis for determination of what type of tax payer the person is but i think its the taxable income figure (£92430)

Appreciate your help.