You make contributions to USS which are tax-free. These contributions are used to build up your pension savings. The Annual Allowance (AA) is the maximum amount of pension savings you can build up each year before you get a tax charge.
The standard AA is currently £60,000 per tax year. If you build pension savings over this you may incur a tax charge. Find out more on the AA.
For more information and options on how to manage your AA, take a look at Voluntary Salary Cap (VSC) and Scheme Pays.