You might not get the full state pension for one of three main reasons:
You were contracted out. You may not qualify for the full flat-rate sum because you were 'contracted out' of the state pension in the past.
Contracting out was a government initiative which began in 1978 and finally ended on 6 April 2016, when the new flat-rate system was introduced. It allowed people who were paying into a workplace or private pension to pay less national insurance towards their additional state pension in exchange for getting a higher private pension.
You're likely to have been contracted out of the additional state pension if you are or were in a salary-related pension (also known as a defined benefit) scheme, or you were in some other types of workplace pension scheme before 6 April 2012. To find out more, see the Gov.uk website.
You're a stay-at-home parent. More than 200,000 stay-at-home parents or carers of under-12s risk losing some state pension because it's their earning partner who's registered for child benefit. Even if your partner's bringing in £50,000 or more a year – the threshold where child benefit starts to reduce on a sliding scale – the non-earner is still entitled to NI credits – so make sure the right person is registered. You can also transfer NI credits from one partner to another to boost your state pension.
You're a women who reached state pension age before April 2016. Tens of thousands of women are likely to have been underpaid the state pension, and many could be due £1,000s – some even £10,000s. Married women who reached state pension age before April 2016, plus widows, divorcees and the over-80s – whether married or not – should check. See our dedicated guide on this for more.