The amount of an individual’s annual pension build-up that is tested against the annual allowance to determine whether that individual is required to pay an annual allowance charge.
For defined benefit schemes, such as the Firefighters' Pension Scheme, the PIA is the measurement of the increase in pension during the Pension Input Period (PIP) multiplied by a flat factor of 16.
Annual pension at 6 April 2016 = £35,000
Annual pension at 5 April 2017 = £38,000
PIA = £38,000 - £35,000 = £3,000 x 16 = £48,000