Just a thought, but failure to pay would also include other possible felonies including filing of false tax returns or fraud. So while technically, they may not prevent your voting under the Constitution for not paying, other crimes associated with not paying would trump that.
I suppose someone who was sent to prison solely for failing to pay taxes, and who lost the right to vote as a result, might try to use the 24th amendment to reclaim his voting rights, but such people are presumably a very small fraction of the felons who are barred from voting.