Maternity pay below 12 000

Hello I am currently on maternity leave and I was paid full for first 3 months then 7 months smp and last 2 months unpaid and I still seem to pay a lot of tax. Could someone please direct me or explain on why am I still getting tax on a low maternity income like this please?

Hi Jowita Holt,
We would need to access your record to check the pay and tax details for you.
Income Tax: general enquiries 
Thank you.