Tiger mate,
If you expect your pension savings to be more than £1.5 millions when you come to take your benefits on or after 6 April this year, you can ring-fence your 'pot' to reduce your taxation liability (from April, the lifetime allowance (LTA) for pensions will be reduced from £1.8 milions to £1.5 millions). The lifetime allowance is the total value of pensions which you can accumulate without incurring additional tax charges. If you are going to exceed this amount, you can however, apply for Fixed Protection (FP), meaning that your LTA would be fixed at £1.8 millions (and not the revised, lower amount).
People who could benefit from applying for FP are those relatively close to retirement, or anyone who believes the HMRC's value of their existing pension provision might exceed £1.5 millions at retirement. In real-life terms, primarily, but not exclusively, this is of interest to people at 2/3* level - especially those who might be about to start a second career in civvy street. Options? Negotiate a second career pay and remuneration package that considers alternatives and isn't so pension based?
You do not need to already have built up pension rights of more than £1.5 millions to apply but you should expect your pension pot contributions to cease if you
do elect to apply for FP. The impact of failing to apply for FP? It could cost up to £75,000 in tax-free cash (especially if you have a second, larger Defined Contribution scheme) while a tax charge would also apply on any monies that exceed £1.5 millions.
HM Revenue & Customs: Fixed Protection for Pension Savings
That is all information - as ever, take personal advice that applies to you.