Membership of UK occupational pension schemes has risen for the first time since 2008, reaching 27.9m in April 2013 – an increase of 300,000 over the year before – according to the Office for National Statistics (ONS).

Active membership rose slightly from 7.8m in 2012 to 8.1m in 2013, following a slow but steady decline from 1991 to 2012, and there were increases for both the private and public sector.

In addition, there were an estimated 9.6m pensions in payment and 10.2m preserved pension entitlements, with some individuals falling into more than one category.

However, although membership has not soared following the introduction of auto-enrolment in October 2012, implementation of the reforms is still at an early stage.

Hazel Clarke, a statistician at the ONS, said: “The reference date for the figures is April 2013, so that’s only six months since auto-enrolment began.

“Furthermore, only the biggest companies – those with 6,000 or more employees – had to put plans for auto-enrolment in place by April 2013. And those intending to use a DB scheme were able to delay this.”

She added: “Furthermore, the reforms are not happening in isolation, and other factors such as employment, disposable household income levels and attitudes to saving for retirement would also affect membership and contribution rates.”

Nevertheless, the ONS said the increase in active membership was likely to be due to the introduction of automatic enrolment in both the public and private sectors, with active membership increasing from 5.1m to 5.3m in the public sector, and 2.7m to 2.8m in the private sector.

It also said some of the drop in active membership of private sector occupational pension schemes in previous years can be accounted for by the growth in the number of employees contributing to group personal pensions.

Fewer than 1% of employees had a group personal pension in 1997; by 2013, this had risen to nearly 12%.

Meanwhile, contribution rates for private sector defined benefit (DB) schemes, excluding deficit reduction payments, remained higher than for defined contribution (DC) schemes.

For private sector DB schemes, the average contribution rate was 5.2% of pensionable earnings for members, and 15.4% for employers.

For private sector DC schemes, the average contribution rate was 2.9% for members and 6.1% for employers.

But within the latter type of scheme, employer contributions have fallen from 6.6% in 2012.

The ONS said this could have been caused by the phasing in of minimum levels for employer and employee contributions, part of the government’s workplace pension reforms, which will last until 2018.

It said this might mean an increase in the number of new members starting on the minimum rates, pulling down the average rate.

But it added that the fall might also be due to employers reducing contributions into existing pensions – referred to as “levelling down”.

Meanwhile, in private sector career average schemes, average employer contribution rates were lower than for DB schemes as a whole.

In 2013, the rate for career average schemes was 12%, compared with 15.4% for all DB schemes.

Average member contribution rates in career average schemes were fairly similar to the average rate for all DB schemes (5.4% and 5.2%, respectively).

The figures also show that, between 2011 and 2013, employer rates for DB schemes have risen slightly, from 14.2% to 15.4% of pensionable earnings.

The ONS said that, although deficit reduction payments as single payments were excluded from the estimates, it may be that schemes increase their regular contribution rates to minimise deficits and/or the risk of falling into deficit.

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