In one case a woman was paid more than £7,000 in arrears but had previously been told all was well despite phoning to query her payments.
The Department for Work and Pensions (DWP) estimates it underpaid 134,000 pensioners and those it can trace will be paid an average of £8,900.
ザ・ 会計検査院 (番号) said repeated human errors were almost inevitable amid complex rules and outdated IT systems.
The NAO’s report into the mistakes highlighted how Sir Steve had approached the DWP with examples of underpayments.
Sir Steve, who is now a partner at consultants LCP (Lane Clark & 孔雀), said he had helped one couple in their 70s from the Midlands.
Irene Wise, 74, で引退 2007 and had a reduced pension because of her national insurance record.
Her husband retired in 2013 and claimed his pension. At that point Mrs Wise’s pension should have been increased to the married women’s rate, but this did not happen.
Following recent publicity she contacted Sir Steve, who raised her case with the department.
It agreed she was underpaid and she was paid more than £7,000 in arrears.
Sir Steve said: “What is shocking about Mrs Wise’s experience is that she actually rang up to query her pension and was told that all was well.
“I have heard similar stories on too many occasions. Even more worrying is that the new NAO report shows that even when it comes to correcting past errors DWP are still making mistakes.
“It is absolutely vital that the highest standards of quality control are now applied both to the correction of past mistakes and to the information that is given out to people who get in touch.”
A Department for Work and Pensions (DWP) 広報担当者は言った: “We are fully committed to ensuring the historical errors that have been made by successive governments are corrected, and as this report acknowledges, we’re dedicating significant resource to doing so. Anyone impacted will be contacted by us to ensure they receive all that they are owed.
“Since we became aware of this issue, we have introduced new quality control processes and improved training to help ensure this does not happen again.”