deductible has no recorded synonym. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is nondeductible.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
(taxes) an amount that can be deducted (especially for the purposes of calculating income tax)
a clause in an insurance policy that relieves the insurer of responsibility to pay the initial loss up to a stated amount
Synonyms, antonyms and the broader and narrower relations for deductible come from Princeton University’s WordNet. Full sources and licences.
acceptable as a deduction (especially as a tax deduction)