The figure that determines income tax band?

Hi,

I’m working my way through Chapter 2 and I’m not so clear as to which cell/figure in the pro-forma income tax computation determines whether a taxpayer is basic rate, higher rate (or additional rate).

Say a taxpayer had the following:

N-S income – £32,500
Savings Income – £750
Dividend income – £750
TOTAL INCOME – £34,000

Based on this, the taxpayer is in the higher rate band and will have a nil rate savings band of £500

But if the taxpayer had qualifying interest of say, £750 deducted, this would give the following:

N-S income (£32,500 – £750) – £31,750
Savings Income – £750
Dividend income – £750
NET INCOME – £33,250

£33,250 puts the taxpayer into the basic rate band.

I’m wondering which figure establishes the income tax band, the cell showing total income (£34,000) or the cell showing total net income (£33,250).

Thanks in advance.