Tax-Free Cash on Defined Benefit Pensions

If you have a defined benefit pension - the kind that promises a guaranteed income for life based on your salary and years of service, rather than a pot of invested money - tax-free cash works quite differently to the simple "25% of your pot" rule that applies to defined contribution pensions. Understanding how commutation works, and the genuine trade-off it involves, is essential before you make what is usually an irreversible decision.

Why defined benefit pensions don't have a "pot" to take 25% from

Defined contribution pensions have an obvious number to apply 25% to: the value of your invested pot on the day you access it. Defined benefit pensions don't work this way. Instead of a pot, your scheme promises to pay you a specific annual pension, usually calculated from a formula based on your salary (or average salary) and the number of years you were a member of the scheme. There's no pot sitting there to take a quarter of - the pension exists purely as a promise of future income.

To provide tax-free cash to defined benefit members, schemes instead use a mechanism called commutation. This means you give up, or "commute," some of your guaranteed annual pension income in exchange for a one-off tax-free lump sum, at an exchange rate set by your specific scheme, known as the commutation factor.

How commutation factors work

A commutation factor expresses how much lump sum you receive for each £1 of annual pension you give up. For example, a commutation factor of 12:1 means that for every £1 of annual pension you give up, you receive £12 of tax-free lump sum. So if you gave up £1,000 of annual pension at a 12:1 factor, you'd receive £12,000 as a tax-free lump sum instead.

This might sound like a fairly technical detail, but the commutation factor your scheme uses has an enormous effect on whether taking the lump sum represents good or poor value, and it varies significantly from scheme to scheme. Some schemes offer commutation factors as low as 12:1, while others offer considerably more generous factors of 20:1 or higher. The higher the factor, the more lump sum you get for each pound of pension given up, and the better value the trade generally represents for the member.

A worked commutation example

Let's say you're entitled to a defined benefit pension of £20,000 a year, and your scheme uses a commutation factor of 15:1. You decide to give up £4,000 of that annual pension in exchange for a lump sum. At a 15:1 factor, that £4,000 of annual pension converts to a lump sum of £60,000 (£4,000 multiplied by 15), paid to you tax-free. Your remaining annual pension, after commutation, would be £16,000 a year rather than the original £20,000.

As the table shows, the same £4,000 of annual pension given up produces very different lump sums depending on the commutation factor - £80,000 at a generous 20:1 factor compared to just £48,000 at a less generous 12:1 factor, for exactly the same reduction in ongoing guaranteed income. This is precisely why it's essential to know your own scheme's specific commutation factor rather than assuming a "standard" figure applies, since there genuinely isn't one standard rate across all UK defined benefit schemes.

Why commutation factors vary so much between schemes

Commutation factors are set by each individual scheme's actuaries, based on assumptions about life expectancy, investment returns, and the scheme's own funding position, rather than being set centrally by government or regulation in the way that, say, the state pension is. Public sector schemes, such as those covering the NHS, teachers, civil service, and local government, tend to have their commutation factors set out clearly in scheme rules and are often reviewed periodically, though the generosity of these factors varies between different public sector schemes and has changed over time as actuarial assumptions have been updated. Private sector defined benefit schemes can set their own factors too, and there's often more variation between different private schemes than there is across the main public sector schemes, since private scheme trustees have more discretion over how commutation terms are structured.

Because of this variation, a commutation factor that looks generous in one scheme might be considered poor value in another, and it's simply not possible to give a universal rule of thumb about whether commuting part of your pension is a good idea without knowing your specific scheme's factor and comparing it to a reasonable estimate of what an equivalent annuity might cost to buy with that same lump sum on the open market.

The trade-off: guaranteed income for life vs a one-off sum

At its heart, commutation is a trade-off between certainty and cash. The pension you give up is guaranteed for the rest of your life, typically increases at least partly with inflation, and in many schemes continues (often at a reduced rate) to a surviving spouse or civil partner after your death. The lump sum you receive instead is a one-off sum, paid tax-free, that you can spend, save, or invest however you choose, but which doesn't come with any of those ongoing guarantees once it's been paid out.

Whether this trade-off makes sense for you depends heavily on your personal circumstances: your health and likely life expectancy, whether you have other sources of retirement income, whether you have an immediate need for a lump sum (such as clearing a mortgage), and how you feel about the balance between guaranteed security and having capital available to use flexibly. Someone in good health with a long life expectancy ahead of them, for instance, might find that giving up guaranteed income for a relatively modest lump sum represents poor value over a potentially long retirement, since they're likely to receive that income for many years. Someone with a shorter life expectancy, or an urgent need for capital, might reasonably weigh the trade-off differently.

Why this decision is effectively irreversible

Unlike some pension decisions that retain a degree of flexibility, commutation is typically a one-time, irreversible choice made at the point your defined benefit pension comes into payment. Once you've decided how much of your pension to commute and received your lump sum, you generally cannot change your mind later, increase the amount commuted, or reverse the decision to receive a higher ongoing pension instead. This finality is precisely why it deserves careful thought rather than being treated as a routine administrative choice - it's one of the more consequential financial decisions many people make at retirement, and it's locked in for the rest of your life (and potentially affects what a surviving spouse receives too).

How commutation interacts with the lump sum allowance

Even though defined benefit commutation works differently from taking 25% of a defined contribution pot, the resulting tax-free lump sum still counts towards the same standard lump sum allowance of £268,275 that applies across all your pensions combined. If you have both a defined benefit pension and one or more defined contribution pots, any tax-free cash you take from any of them - whether via commutation or the standard 25% rule - draws down against the same overall allowance. This matters particularly for members of generous public sector schemes with long service, where the maximum available tax-free lump sum from commutation alone can sometimes approach a meaningful proportion of the allowance, leaving less headroom for tax-free cash from other pensions you might hold.

It's also worth knowing that most defined benefit schemes impose their own maximum limit on how much of your pension you're allowed to commute, often expressed as a percentage of the notional value of your pension for allowance purposes, rather than allowing unlimited commutation up to the lump sum allowance cap. In other words, your own scheme's rules, not just the lump sum allowance, may be the practical limiting factor on how much tax-free cash you can generate through commutation.

Public sector schemes vs private sector schemes

Public sector defined benefit schemes - covering groups such as NHS staff, teachers, civil servants, firefighters, police officers, and local government workers - generally have commutation factors set out in published scheme rules, which can make it easier to look up your own scheme's specific terms in advance. These factors have been reviewed and adjusted over time as life expectancy assumptions and actuarial calculations have evolved, and different public sector schemes can have noticeably different factors from one another, so it's a mistake to assume "the public sector rate" is a single, consistent figure across the whole of the public sector.

Private sector defined benefit schemes, which are increasingly rare for new members but still cover many people with historic entitlements from past employment, often set commutation factors at scheme level based on their own actuarial advice, funding position, and trustee decisions. This can result in more variation between individual private schemes than you'd typically find across the main public sector schemes, making it especially important to check your specific scheme's factor rather than assuming a general private sector norm applies.

What happens to a surviving spouse or partner

One further consideration that's easy to overlook is the effect commutation has on any pension payable to a surviving spouse, civil partner, or dependant after your death. Many defined benefit schemes calculate a spouse's or dependant's pension as a percentage of your own pension - commonly around half - meaning that if you commute part of your pension for a lump sum, you may also be reducing what a surviving spouse or partner would subsequently receive, not just your own income. This is a significant factor to weigh, particularly if your spouse or partner has limited pension provision of their own and would be relying substantially on a share of your defined benefit pension after your death. It's well worth checking exactly how your specific scheme calculates spouse or dependant benefits, and whether commutation reduces that calculation, before deciding how much of your pension to commute.

Ill health and enhanced commutation considerations

Some defined benefit schemes offer different, sometimes more generous, commutation arrangements for members retiring due to ill health, reflecting the shorter life expectancy that may be involved in some ill-health retirement cases. If you're retiring on grounds of ill health, it's worth specifically asking your scheme administrator whether any different commutation terms apply to your situation, since the standard factors and considerations described above may not directly apply in the same way.

Comparing commutation to defined contribution tax-free cash

It's useful to hold the defined contribution and defined benefit approaches to tax-free cash side by side to see how differently they work. With a defined contribution pot, taking 25% tax-free doesn't reduce any ongoing guaranteed income, because there isn't one - you're simply taking a portion of your own invested money tax-free, and the rest remains available to generate income however you subsequently choose to access it. With a defined benefit pension, by contrast, every pound of tax-free lump sum you take through commutation comes directly at the cost of guaranteed income you would otherwise have received for the rest of your life. This is the fundamental reason why the decision deserves more individual scrutiny for defined benefit members than the equivalent decision for defined contribution savers, where taking your 25% doesn't carry the same permanent income trade-off.

Questions worth asking your scheme before deciding

Before committing to a commutation decision, it's worth requesting a clear illustration from your scheme administrator that answers a specific set of questions: what is the exact commutation factor for your scheme, what is the maximum amount you're permitted to commute under scheme rules, how would commuting affect any spouse's or dependant's pension, and does your annual pension increase with inflation in a way that a lump sum, once spent or invested elsewhere, would not automatically replicate. Having clear answers to each of these before you decide gives you a far more complete picture than simply comparing the headline lump sum figure against your current annual pension in isolation, and it turns what can feel like an abstract, jargon-heavy decision into a concrete comparison you can genuinely weigh up.