The legislation, which will slash corporate taxes as well as cutting those for individuals, has been criticized as primarily benefiting the wealthy.
The measure is President Donald Trump's last shot at a major legislative accomplishment in his first year in office.
CBS News reported that McCain, who was hospitalized for side effects of chemotherapy treatment for brain cancer, returned to Arizona today and would miss the tax overhaul vote.
CNN also reported that McCain would miss the vote, which is expected to be held in the next few days.
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"My father is doing well and we are all looking forward to spending Christmas together in Arizona," she wrote on Twitter.
If McCain is absent, Republicans -- who have a 52-48 majority in the Senate -- can only afford one defection if the measure is to pass.
No Democrats or independents support the legislation in the Senate. It is expected to comfortably pass the House.
McCain, an 81-year-old former prisoner of war and 2008 Republican presidential nominee was diagnosed in July with a brain tumor known as a glioblastoma, after doctors found a blood clot over his left eye during a routine checkup.