The 12-year lock-up isn't theoretical
Take £60,000 today as an employer pension contribution. You cannot touch a penny of it until age 57 — rising from age 55 in April 2028. For a director aged 45 today that's twelve years; aged 40 it's seventeen. In between, life happens.
Mortgage rates today sit around 5.14% for a 75% LTV two-year fix. The Bank of England base rate is 3.75% and falling, which means cash savers are losing real yield to the 3.3% CPI print. Overpaying that mortgage with £31,404 of post-dividend-tax cash earns a guaranteed, risk-free 5.14% — equivalent to an 8.6% pre-tax return for a higher-rate taxpayer. The pension contribution earns a higher paper return only if you actually hold to 57. Most directors don't.
ABI data shows that around a third of small company directors who fund SIPPs end up needing some form of equity release, redirected dividends, or business sale before retirement. Locking up a year's surplus profit in a wrapper that you can't touch — for a marginal tax saving the government can amend overnight — is the kind of decision that looks clever in a spreadsheet and reckless in a divorce.