You will receive tax relief on your contributions, up to 100% of your taxable earnings. This is subject to the Annual Allowance.
The Annual Allowance is the maximum amount of pension savings you can make across all pensions in any tax year, which benefit from tax relief. If your pension savings in a year are more than the Annual Allowance, you might have to pay some tax on the amount over the Annual Allowance.
You can read more about the Annual Allowance by visiting the Tax on your private pension page on the GOV.UK website.