When you pay for AP by regular monthly instalments, you'll receive any tax relief you're eligible for through your monthly salary.
The tax relief is received by paying pension contributions on your gross taxable earnings and income tax on your remaining salary.
If you've chose to make a lump sum AP contribution, you can claim any tax relief you're entitled to by completing a self assessment tax return. This must be sent to HM Revenue and Customs (HMRC).
Contact HMRC directly for further information on tax relief.