Hello and welcome to the site. Thank you for your question.
In basic terms, the annual allowance is a limit on the amount that can be contributed to your pension each year, while still receiving tax relief. It's based on your earnings for the year and is capped at £40,000.
You would have to fully utilise this year's allowance first and any excess could be utlised against previous years 3 years.
If your earnings are £60,000 and you have not made any contributions into a pension plan, you could contribute £40,000 in the tax year 2014-15 plus another £20k from remaining allowance - see below.
Your annual allowance for 2011/12 to2013/14 was £50k each year and your contributions were £30k in each year.
Annual allowance remaining is
2011/12 - £20k
2012/13 - £20k
2013-14 - £20k
Your question is would you gain anything from putting £50k into the pension pot ... the answer is yes as your contribution would get you tax relief at your marginal rate.
The alternative would be to save this sum into other investments providing a much lower yield.
I hope this is helpful and answers your question.
If you have any other questions, please ask me before you rate my service – I’ll be happy to respond.