700,000 people may be due state pension back payments

The expert also highlighted the key groups who could be affected by underpayments: married, widowed and over 80s – all of whom reached state pension age before April 2016.

According to Standard Life, it is possible men may be eligible for underpaid state pension top-ups.

However, men are more likely to have a full National Insurance record, and less likely to rely on a spouse or partner for a state pension top-up.

Not everyone will have their state pension updated automatically, so it is important to stay alert.

Whether or not a person has been underpaid will depend on individual circumstances.

As a result, some individuals will need to take action.