The government sets a limit on how much you can pay in to your pensions every year before incurring tax charges. This is called the 'annual allowance'. For the 2021/22 tax year, the standard annual allowance is £40,000. This is a combined total across all of the pensions you're paying into. It could be lower, depending on your individual circumstances.
There’s also a 'lifetime allowance', which is a limit on the combined amount you can take from your pensions before you receive an extra tax charge. The current lifetime allowance is £1,073,100.