Tax query on PPI refund tax

I have successfully reclaimed PPI on several old cards, I am a non taxpayer so decided to reclaim the tax I paid on the refund, the total tax paid on the refunds (£2500) will take me over the income tax threshold.
I am assuming that I will only pay tax on the difference between the tax threshold and the final amount, so it will take £1000 to take me to the threshold and £1500 over the threshold so I will only pay tax on the £1500.
Am I correct ?