Claiming deduction for subscriptions to professional bodies

I have looked at the View my Calculation page and can see that HMRC have deducted the whole amount I pay to a professional body. I thought HMRC only allowed me to claim a certain amount of the subscription , not the entire amount. Any idea why the whole amount has been deducted from my final tax bill ? Thank you.

Hi,
The calculation is based on the information you have entered.
The system will not make any adjustment on your behalf and you therefore need to enter only the amount you are entitled to claim and not the full subscription.
Thank you.