'I claimed back 14 years' worth of council tax for my dad who had a stroke'

Melanie was able to claim back 14 years' worth of council tax payments for her father, after realising he may be exempt from paying while watching Martin Lewis on TV, and researching the 'severely mentally impaired' (SMI) discount on MoneySavingExpert.com.

Her father had a severe stroke in 2005 and began receiving attendance allowance, which is a type of benefit paid to disabled people of state pension age.

And after she submitted a claim, Southampton City Council – her father's local council – automatically backdated the reclaim to this date. Her father also won't have to pay council tax in the future.

See How to claim the 'severely mentally impaired' council tax discount for more information.

What is the SMI discount?

To get an SMI discount, someone must be medically certified as having a severe mental impairment (ie, one that severely and permanently affects their intellectual and social functioning).

This is a medical diagnosis in itself, but the underlying cause could be a condition such as dementia (including Alzheimer's), severe learning difficulties or something else. It's important to note that having an underlying condition does not automatically mean a person is SMI.

If someone is diagnosed as SMI, they can be 'disregarded for council tax purposes' in England, Scotland and Wales – in a similar way that students are, for example. If you're diagnosed as SMI, this means you can claim:

• A 25% discount – if you live with someone who's 'severely mentally impaired' and no other adults, or only adults who have also been disregarded for council tax purposes. Effectively, you get a single person's discount – but when claiming, specify you require a discount because you are living with someone who is 'severely mentally impaired'.

• A 100% discount – if you're 'severely mentally impaired' and live alone, you shouldn't be paying any council tax at all.

There are full details on who is eligible and how to claim for the discount in our guide.

Unfortunately not all councils allow you to backdate reclaims (though we think they should), some will only stop you paying in the future. Luckily for Melanie and her dad, Southampton City Council is one of the authorities that does backdate reclaims.

'I'd definitely never heard about the discount before'

Melanie said: "After watching Martin Lewis on TV a few months ago, I investigated the discount on MoneySavingExpert.com. I'd definitely never heard about this discount before."

Several weeks after applying she was told the claim had been accepted, but in order to backdate it, the council would write to the Department for Work and Pensions to confirm when her dad began receiving the attendance allowance. At the end of July, she was told just over £14,000 would be paid into her dad's account.

She added: "The whole process was very easy and I'd like to thank Southampton City Council as well as Martin, because without him I'd never have realised my father could be entitled to this discount."

'This is a whopping pay out'

Kirsty Good, head of campaigns at MoneySavingExpert.com, said: "This is a whopping payout for this family. Being diagnosed SMI means you're really poorly and for many people, like Melanie's dad, being fully exempt from paying council tax and getting a rebate of this size is crucial to their care. It can really improve their quality of life and even help them stay living at home that bit longer.

"But the travesty is that in reality, claiming this discount is a postcode lottery. It exists to help some of society's most vulnerable, but we know from our campaigning that too many councils are giving out some form of wrong information about the discount and, disgracefully, some claim the discount doesn't exist. Even if potential claimants do get the right information, there are huge differences in take-up across the country and inconsistencies in backdating policies.

"There should be a standard application process for all councils, with clear rules on rebates and better training for frontline council staff. Working with MSE, Wales has led the way in doing this, making the discount fair and accessible for all its residents, with a consistent approach and one form across all 22 local authorities. Now it's time for Scotland and England to follow suit."

What does Southampton City Council say?

A Southampton City Council spokesperson said: "We actively promote council tax exemptions for severely mentally impaired (SMI) residents through our website and via billing information sent to households.

"Any application is dealt with promptly and on a case-by-case basis, with the award of SMI being applied from the date the applicant first became eligible."