As well as the 25% single person payment, you can get a reduction if you are on a low income. If you go to one of the sites (turn2us or entitledto - I think the latter is the official government site) you can work out whether you are entitled to a reduction by putting in your details, income etc. You also put in which borough council you come under. I think the sites can work it out more or less exactly, but I think it can vary depending on the particular council you are under. There's no harm in applying to your council as they can't charge you more than the 25% and you may be able to pay less and get a refund on this year's bill.