Do Jehovah Witnesses believe it is immoral to pay for blood transfusions through taxation? I’m having a discussion about abortion and taxes, and it was mentioned that Jehovah Witnesses have to pay taxes that fund blood transfusions.
Do Jehovah Witnesses believe it is immoral to pay for blood transfusions through taxation?
I found an article from the Jehovah’s Witness official web site that indirectly answers your question.  It uses the example of governments using income taxes to pay for wars and points out that it is the responsibility of governments to decide how tax payers’ contributions are spent:
Watchtower 1 April 1975 – Are you guided by a sensitive Christian conscience?  Paragraph 4: For example, a person might recognize that Jehovah is not backing the wars of the nations, but that he urges his people to learn the ways of peace. (Isa. 2:4) Knowing that usually the nations support their armies with tax money, would it be balanced and Scriptural for his conscience to lead him to refuse to pay taxes? Or to pay his taxes minus a percentage corresponding to what the government spends on its defense budget? While some persons have taken such a stand, the Bible evidence weighs against a conscience that leads to such a course. Christians are plainly told to pay their taxes, and this was put in the Bible despite the fact that the then-existing Roman government supported a vast army. (Matt. 22:17-21; Rom. 13:1, 7) Thus the Christian can, with a clear conscience balanced by God’s Word, pay his taxes, leaving with the governments the responsibility of how the money is used.  https://wol.jw.org/en/wol/d/r1/lp-e/1975246#h=4:0-8:330
A Jehovah’s Witness therefore has a clear conscience when it comes to paying taxes – how the government decides to use that income is not the responsibility of the Witness.