These are backdated contributions that you would have paid if you had joined the scheme between 1 July 2000 and 5 April 2006, up to the date at which you chose to join. You must pay these contributions in order to be treated as a special member of the FPS 2006. You could choose to pay the contributions by a single lump sum or periodically along with your basic contributions.
A lump sum would have to be paid within 6 months from the date of choosing to join – failure to pay within this period would mean that your election to join would be treated as not having been made.
Periodic contributions (plus interest) would be paid over a period of 10 years, starting after the date of election. If you are paying by this method and retire within those 10 years and before payment has been completed, there would be an option to pay the balance of contributions as a lump sum within three months of becoming entitled to receive payment of the pension. Payment could be made by a deduction from any lump sum by commutation.
If payment is not made in full, the period of special pensionable service due to be credited will be adjusted according to contributions paid as a proportion of contributions due. The exception to this would be if you were to die in service. Then, full credit of special pensionable service would be given, and used in the calculation of survivor benefits.