A self-invested personal pension (SIPP) is the name given to the type of UK government-approved personal pension scheme which allows individuals to make their own investment decisions from the full range of investments approved by HM Revenue and Customs (HMRC).
SIPPs are "tax wrappers", allowing tax rebates on contributions in exchange for limits on accessibility. SIPPs are tax-efficient investment vehicles as they allow investors to receive income tax relief on their contributions at their highest marginal tax rate. Any contributions from employers will reduce their corporate tax liability. The investments can grow tax-free, a lump sum can be taken by the investor tax-free on retirement, and SIPPs attract better inheritance tax treatment if the beneficiary dies before the age of 75.
The HMRC rules allow for a greater range of investments to be held than personal pension schemes, notably equities and property. Rules for contributions, benefit withdrawal etc. are the same as for other personal pension schemes. Another subset of this type of pension is the stakeholder pension scheme.