Expert names one SIPP mistake that can severely dent your pension pot | The IndependentJump to contentSwipe for next articleIndependent Bulletin homepageDownload our appAllNewsSportCultureLifestyleWant to bookmark your favourite articles and stories to read or reference later? Start your Independent Premium subscription today.Subscribe`; document.body.appendChild(modal); modal.addEventListener('click', () => { document.cookie = 'mos-plan-select=; Max-Age=0; path=/; expires=Thu, 01 Jan 1970 00:00:00 UTC;'; }); modal.querySelector('.subscribe-link')?.addEventListener('click', (e) => { e.preventDefault(); document.cookie = 'mos-plan-select=; Max-Age=0; path=/; expires=Thu, 01 Jan 1970 00:00:00 UTC;'; setTimeout(() => { window.location.href = 'https://www.independent.co.uk/subscribe/app'; }, 500); });});]]>Lori CampbellThursday 17 September 2026 08:08 BSTMe, Myself and Money: SIPPs, pensions and financial lessons with Big Brother’s Anthony HuttonHolding excessive uninvested cash within personal pensions (SIPPs) and stocks and shares ISAs can significantly drag down long-term portfolio growth due to inflation and missed market rallies.Financial advisers recommend keeping three to six months of emergency funds in easy-access savings outside investment platforms, whilst maintaining low cash balances of around two per cent inside long-term investment accounts.Vanguard's James Norton highlights that £10,000 invested in global equities 20 years ago grew to £82,500 accounting for inflation, compared to reducing in purchasing power to just £4,100 if retained as cash.Investment platform policies on uninvested cash vary substantially, with some providers offering competitive interest rates and others paying little to no interest, which can cost investors hundreds of pounds annually on larger balances.Tax treatment differs across account types, with cash interest inside SIPPs and ISAs enjoying tax-free status, whereas uninvested cash in general investment accounts counts towards personal savings allowances and is subject to income tax.In fullThis is how much cash you should really keep in your SIPP for investingMore bulletinsThank you for registeringPlease refresh the page or navigate to another page on the site to be automatically logged inPlease refresh your browser to be logged in