Hi M22,
To work out your adjustable net income, you add up your taxable income and subtract any 'tax reliefs'.
Personal Allowances: adjusted net income advises that "'tax relief' means that you either pay less tax to take account of money you’ve spent on specific things, like business expenses if you’re self-employed or get tax back or get it repaid in another way, like into a personal pension".
For this reason, qualifying load interest does not reduce your adjustable net income.
Thank you.