AP can be purchased either by a lump sum or by regular monthly contributions over a pre-specified term. The costs are shown per £250 pa of AP purchased.

Generally, factors for calculating the cost to a member of AP should be selected with reference to the member's:

• age (last birthday) at election
• expected normal pension age (NPA) at retirement (NPA is defined as a member's State Pension Age (or 65, if that is higher) in the STPS - for the purposes of this note, a member's expected NPA in the STPS is the same as their State Pension age as set out in HM Treasury's Directions),
• chosen form of payment (either lump sum or regular contribution), and
• chosen form of benefit (either member only or member with dependant).

Where the AP is not purchased by a lump sum, factors must additionally be chosen with reference to:

• the date of election, and
• the period of contributions as at the election date (between 1 year and 20 years).

Where the member has a non-integer NPA a contribution rate is calculated for the member's NPA rounded down to the nearest whole number. A further contribution rate is calculated for the member's NPA rounded up to the nearest whole number. These figures are interpolated to obtain the actual contribution rate.

Where the member elected to purchase the regular contribution AP contract on or after 1 April 2011, the AP will increase in line with Consumer Prices Index (CPI) before coming into payment.

Where the member elected to purchase the regular contribution AP contract before 1 April 2011, the AP will increase in line with Retail Prices Index (RPI) before coming into payment.

Factors for new lump sum elections are contained in Tables 702 to 705 of the Consolidated Factor Workbook. If the original election date is on or after 1 April 2011, and the member originally purchased additional pension subject to NPA60 through a monthly contribution, then please refer to GAD.

Factors for regular contribution elections made on or after 1 April 2011 are contained in Tables 706 to 715.

Factors for regular contribution elections made before 1 April 2011 are contained in Tables 716 to 719.

Factors for the purchase of the outstanding amount by lump sum (for elections made before 1 April 2011) are contained in Tables 720 to 721.