Mothers are being encouraged to check whether they may be entitled to some additional cash after being underpaid state pension money.
Consultants LCP have launched a campaign urging people to check their entitlements. Since the late 1970s, the state pensions system has included measures to protect parents with gaps in their National Insurance (NI) records because of time spent out of paid work bringing up children.
The system was originally called "home responsibilities protection" (HRP) and is now known as National Insurance credits. Sir Steve Webb, a former pensions minister who is now a partner at LCP said: "Yet again, this error overwhelmingly affects women, and undoubtedly means that many thousands have been underpaid for years.
