Your Workplace Pension Default Is Designed by HR, Not by Investors — Open a SIPP and Stop Subsidising Mediocre Funds

The auto-enrolment default funds aren't disclosed in your monthly payslip. They sit on page 11 of the annual statement nobody reads. Pull yours up: the Pensions Regulator requires the AMC to be quoted prominently and the FCA's consumer pensions guidance explains how to find it.

The big four auto-enrolment providers in 2026:

• NEST: 0.30% AMC + 1.8% contribution charge on every pound paid in. The 1.8% headline charge is the trap — over a 30-year working life it costs proportionally as much as a 0.45% AMC.
• Aviva My Future Focus: 0.30-0.40% AMC, lifestyling glide-path that de-risks aggressively from age 50.
• Aegon BlackRock LifePath: 0.35-0.45% AMC depending on employer tier, BlackRock-managed multi-asset default.
• Scottish Widows Pension Portfolio Two: 0.40-0.55% AMC, oldest scheme architecture of the four, frequently the most expensive default.

Now the SIPP comparison. Vanguard's UK SIPP charges 0.15% platform (capped at £375/yr) plus 0.18% on its FTSE Global All Cap tracker = 0.33% total. InvestEngine charges 0% platform on its core ETF range plus 0.18% on a Vanguard or HSBC global tracker = 0.18% all-in on small pots. AJ Bell: 0.25% platform plus 0.18% on a global tracker = 0.43%.

On the cheapest SIPPs you're paying 0.18%-0.33% all-in. On a typical workplace default you're paying 0.35%-0.50% all-in. The gap of 0.10-0.30% a year doesn't sound dramatic until you multiply by 25 years and a six-figure pot.

Run the numbers. £100,000 starting balance plus £200/month contributions, growing at 5% real for 25 years.

• At 0.45% AMC (typical workplace default): ending balance £429,000
• At 0.30% AMC (cheap SIPP via Vanguard): ending balance £445,000
• At 0.18% AMC (InvestEngine on Vanguard ETF): ending balance £458,500

The gap between the cheap SIPP and the typical workplace default is £16,000-£30,000 over 25 years. The salary-sacrifice argument the SIPP critics lean on — 8% employee NI relief on contributions — saves a basic-rate employee about £192 a year on a £200/month contribution. Even if your employer rebates half their 15% employer NI saving (most don't, after the 2025 secondary-threshold cut), that's another £180. Total NI advantage: £372/year for 25 years = £9,300 of extra contributions, which at 5% real growth compounds to roughly £19,500 of extra pot.

SIPP fee saving over 25 years: £16,000-£30,000. NI advantage over 25 years: £19,500 (and that's the optimistic case with a generous employer rebate).

It's close. The SIPP wins on a typical 0.45% workplace fund. It wins decisively on an older 0.55%+ scheme. It loses only against a top-decile workplace at 0.25-0.30% AMC where the employer rebates the full 15% NI saving.

Cost is one half of the case. The other half is what you're allowed to buy. A typical workplace fund range offers 6-15 options: a default lifestyling fund, an ethical/ESG variant, a UK equity fund, maybe a global equity fund, a bond fund, an annuity-target fund, and a cash fund. That's it.

A SIPP holds anything tradeable on the LSE plus a wide range of unit trusts and OEICs. You can build a 70/30 global equity / bond portfolio with a 0.07% Vanguard VWRL ETF and a 0.10% iShares Core UK Gilts ETF. You can tilt to small-cap value, emerging markets, REITs, or commodities if your strategy calls for it. You can hold individual gilts to maturity — the DMO lists every gilt issue and a SIPP can buy them at primary auction or in the secondary market.

The workplace default lifestyling fund will start de-risking you into bonds and cash from age 50, regardless of your personal retirement plan. If you're targeting age 65, you don't want a 50-year-old's portfolio sitting in 30% gilts by age 55 — those gilts are likely to compound at 3.8-4.5% (per current 10-year gilt yields of roughly 4.7%) when the equity portion would average 5-7% real. The default fund makes you safer than you need to be at exactly the wrong time.

None of this is fixable inside the workplace scheme. The fund menu is what it is. The lifestyling target is what it is. You can sometimes opt out of the lifestyling glide-path and pick a 'self-select' equity fund, but you're still bound by the workplace fund universe.

One of the few legitimate arguments for staying inside a workplace pension is the platform-failure risk. The argument runs: workplace schemes have trustee oversight and master-trust regulation; SIPPs are platforms; platforms can fail.

The failure risk is real but small. SIPP platforms are FCA-regulated investment firms covered by the FSCS investment compensation limit of £85,000 per person per failed firm. For pension pots above £85,000 you'd want to either split across two SIPP providers or accept the residual risk. Workplace pensions sit under the Pensions Regulator and have no FSCS investment cap — the assets are held in trust and would survive employer or provider failure.

In practice, a Vanguard or AJ Bell SIPP collapsing is a tail risk in the same magnitude as a major UK bank failing on a non-deposit basis. Worth thinking about above £85,000, but not a reason to leave £15,000-£60,000 of overpriced workplace AMC on the table for two decades. Once your SIPP exceeds the FSCS limit, split it. That's a £20 administrative job once every few years.

The more interesting risk is the workplace one: your employer changes scheme administrator every 4-7 years, your pot gets shunted to a new provider with a different fee structure and a different default fund, and nobody tells you the AMC just went from 0.30% to 0.45%. That's happened twice to me. With a SIPP, the platform doesn't change unless you change it.

The pragmatic routing is this:

1. Always fund the workplace pension up to the employer-match limit. If your employer matches 5% of salary at 5%, that 5% match is a 100% return on contribution. No SIPP touches that.
2. Once the match is captured, model the workplace AMC vs your SIPP option. If the workplace is below 0.35% AMC and the employer shares the 15% NI saving on sacrificed contributions, stay there. Otherwise the SIPP wins long-term.
3. Open a SIPP for the rest of your discretionary pension saving. Use a low-cost platform — Vanguard, InvestEngine, or AJ Bell — and a global tracker. Aim for sub-0.35% all-in.
4. Consolidate old workplace pots from previous employers into the SIPP. This is where the fee saving compounds hardest, because those old pots have decades to grow and the AMC delta is usually the widest.

For the salary-sacrifice mechanics on bonuses, see the £40,000 bonus sacrifice maths. For pension consolidation specifically, our PensionBee review covers the trade-off between consolidator platforms and a self-directed SIPP. The pensions hub ties together annual-allowance rules and the £60,000 limit.

The workplace default isn't villainous. It's adequate. Adequate is not what compounds well over 25 years.

This article is for informational purposes only and does not constitute financial advice. Pension and tax rules are complex and depend on individual circumstances. You should seek independent financial advice before making any pension or investment decisions.