If your pension savings for a year exceed your annual allowance (AA), either you or your pension provider must pay the tax.
The first step is filling in the “Pension savings tax charge”’ part on your tax return. For help, look at form SA101 and use HMRC’s HS345 pension savings
help sheet (see the links below).
Use Box 10 on the Pensions Savings Charges page if you have a charge, even if the scheme pays some or all of it. If they contribute, put the amount they
pay in Box 11. You will need your scheme’s Pension Scheme Tax Reference to fill in Box 12.
If you forget to report the AA charge on your tax return you have twelve months from the filing deadline to amend it. For example, if you forget something
off your 2018/19 return, which had to be filed by 31 January 2020, you have until 31 January 2021 to notify HMRC.
For the SA101
For the HS345