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Form 8915-B-T (for the repayment of deferred tax on Qualified Disaster Retirement Plan distributions) ≠ Form 8615

 

And to answer the original question.  Because the IRS is slow and understaffed.  Just be ready to file for a free extension come April which is pretty easy though it sucks having to wait for the IRS to finish their forms to be able to get your refund.