I think @Chasingsquirrels and @CheeseWineFigs are absolutely spot on. I'm no pensions expert, but you put in £8k, the government adds £2k.
If you are a 40% taxpayer, you can go through HMRC's website to claim the additional back as private pension tax relief, but you have to do this, it doesn't happen automatically. Some people may say "what is the point", I guess there are a few "points", the first is just the maths of putting £8k into something and receiving £10k of benefit (albeit at the risk of funds gong up and down), the second point is that some people will benefit from the additional tax relief if they are 40% tax payers, the third is that child benefit has an impact for some (i,e if your earnings are over the amount that is eligible for child benefit, paying a lump into your pension can reduce these to below the threshold for child benefit not to be taken away, this can mean an additional £1352 for some per child) and finally, if you are close to pension age, you have, at the moment the ability to take 25% tax free as soon as you draw down your pension. So ignoring the child benefit angle, and using a very simple calculation where there is nothing in my pension, if I pay £8k into my pension in July (and govt pays £2k) so £10k in the funds, then I retire in August, I can immediately draw down £2.5k tax free, leaving £7.5k in the fund. This is a ridiculously simple and unrealistic example, and there are some real banana skins out there (one is the limit that you can take tax free which is currently quite high at £268k and probably doesn't affect most people) Another is if you take more than the 25% tax free, even £10 more, then you are limited to what you can pay into a pension pot in the future (to £10kpa), not a problem for people who are "retiring forever" maybe, but for those who maybe go back to work after "retiring" this is a hard lesson to learn. As ever with pensions, you are never going to get "personal advice on your exact situation" unless you pay someone to provide it. Schemes are different, rules are different. You can go to Pensionwise (for free) and they will help you understand the general guidelines and how it works, and there may be scenario based situations used that can help your understanding, Also ringing your pension provider and talking can help. Forums like this can help too, but you do have to do your own research. If pension planning is used well, it can hugely improve financial outcomes later in life, and can, sometimes, help your tax bill now, but it is a bit of a minefield. I hope this helps x