Some women who have been on maternity leave from work could be owed thousands of pounds by their employer, according to an advocacy group.

While on maternity leave, employers are meant to continue matching employee's pension contributions at the same level as before, even if their pay while on maternity leave is lower. 

This requirement applies if someone is entitled to Statutory Maternity Pay, Maternity Allowance or has an enhanced contractual maternity pay arrangement. 

'The mistake some employers have been making is reducing their employer contribution to be based on the employee's maternity pay rather than their pre-maternity salary', Nugget Savings told This is Money.  

Advocacy group Nugget Savings said it had been notified of errors by more than 200 women. It remains unclear how extensive the issue is or it if is a widespread problem.  

Nugget Savings found the blunder had resulted in some women losing hundreds or even, in one case, £4,000, in pension contributions. 

The findings by Nugget Savings were initiated after a member of their community got in touch to explain that her employer pension contributions from a small business she worked at had been reduced since going on maternity leave. 

Nugget Savings raised the issue with the woman's employer and the employer's accountants. The accountants confirmed a mistake had occurred. 

The small business' accountants spoke to the software team behind the accounting operations and HM Revenue and Customs to make further enquiries.

The accountancy firm working for the small business involved was told that there appeared to be a 'national issue' that could have been ongoing for a number of years, potentially leaving many women out of pocket when it comes to employer pension contributions. 

Nugget Savings said it believed the problem could date back to 2012 when pension auto-enrolment was launched. 

It told This is Money it had been made aware of cases where women working at law firms had been affected by employer pension contribution miscalculations during maternity leave. 

More than 200 Nugget Savings members later came forward stating that they had suffered the same problem regarding employer pension contributions. 

The advocacy group said: 'As it stands, the money recovered is in the tens of thousands, just from 200 women.' 

It added: 'Some of our community have been able to reclaim the money from their employer, some people have reclaimed the contributions less the compound interest, and others have been refused repayments by the employers despite them being within their rights.' 

Speaking to This is Money, Katie Guild, co-founder of Nugget Savings, said she was 'deeply concerned' that some women who have taken maternity leave in the last 10 to 15 years may have missed out on employer pension contributions. 

She added: 'This is very bad news for the gender pension gap and yet another way women are penalised for having children. 

'The guidance for employers is unclear and often contradictory - so mistakes are being made which harm the future of working mothers. 

'Clearer guidance from the government is needed, both on the correct procedure for employer contributions during maternity leave and on the steps women should take to reclaim their lost contributions.' 

It is important to note that the number of women who flagged the issue to Nugget Savings remains small. There remains no certainty as to how widespread the issue is or if it is widespread. 

This is Money has contacted The Pensions Regulator for comment.

What are the rules?

If you are on maternity leave, your employer must continue paying pension contributions based on your full salary, not just your reduced maternity pay. 

But payroll mistakes happen, and some employers are not following the rules, leaving new mums with a pension shortfall they might not even realise.

Fiona Peake, a personal finance expert at Ocean Finance, told This is Money: 'Whilst on paid maternity leave (up to 39 weeks with Statutory or contractual Maternity Pay), your employer's contributions should still be based on your usual salary, even though your own contributions are calculated on what you actually earn. 

'Since Statutory Maternity Pay drops to £172.48 a week after six weeks (rising to £184.03 in April), your contributions may shrink, but your employer's shouldn’t.

'If you’ve returned to work part-time or on a lower salary, your pension contributions will naturally drop, but that’s very different from your employer underpaying while you were on maternity leave. 

'If you’ve taken maternity leave in recent years, check your pension statements now to make sure you haven’t missed out.'

Peake added: 'It’s hard to put an exact number on it, but it’s likely that thousands are missing out on pension contributions due to payroll errors. Many won’t realise until much later, when it’s harder to fix.'

Six steps to take if you may be affected 

Ian Hurst, an employment solicitor at Duncan Lewis, shared six tips with This is Money for anyone concerned they might be affected by pension contribution miscalculations during maternity leave. 

 1. Review your contract and pension policy

Examine your employment contract and any associated pension documentation to understand the terms regarding pension contributions during maternity leave.

Typically, during the first 26 weeks of maternity leave, known as ordinary maternity leave, employers are required to maintain their pension contributions based on your full salary, irrespective of any reduction in actual earnings during this period. 

2. Consult Your HR or payroll department

Approach your human resources or payroll department to discuss the discrepancy. Mistakes can occur, and a direct conversation may lead to a swift resolution. Provide them with specific details from your contract and relevant regulations to support your case. 

3. Submit a formal grievance 

If the issue remains unresolved after informal discussions, initiate a formal grievance process. Draft a written complaint detailing the discrepancy, referencing your contractual terms and the legal obligations of the employer concerning pension contributions during maternity leave. 

4. Seek external advice

Should internal processes not yield a satisfactory outcome, seek external guidance. If you're a union member, consult your union representative for support. Additionally, organisations like ACAS and MoneyHelper offer free advice on such matters. 

5. Engage lawyers if necessary

If all other avenues have been exhausted without resolution, consider consulting an employment lawyer. They can provide specialised advice and, if necessary, assist in pursuing legal action to recover any owed pension contributions.

6.  Maintain personal records

Keep detailed records of your communications with your employer, including emails and letters, as well as copies of your payslips and pension statements. This documentation can serve as evidence if you need to escalate the issue or seek legal advice.