Adjusting your taxable income to save tax

perplexedconsumer

I am confused - according to my draft tax return I have taxable income just above £100k but the tax calculation is still giving me the full personal allowance . 
Why is that - what deductions are made in calculating whether you have gone above the £100k threshold where you start losing the personal allowance?  Do gift aid donations count . Does anyone know about this ? If it's correct its a good way of saving some  tax by making a small donation to bring the adjusted total  income below £100k

Dazed_and_C0nfused

Gift Aid and relief at source pension contributions are the common two which reduce your adjusted net income.