Meaning of ALLOWABLE in English
al ‧ low ‧ a ‧ ble /əˈlaʊəb ə l/ BrE AmE adjective
1 . acceptable according to the rules SYN permissible :
The maximum allowable dosage is two tablets a day.
2 . allowable costs are costs that you do not pay tax on:
allowable deductions such as alimony and business expenses
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012