When ALL of your forms in your return are ready to file and you can pass thru the REVIEW tab cleanly the option to pay with the refund will be presented in step 1 of the FILE tab. However this is not a wise choice if you can pay the fees upfront with a CC or Debit card.
If you qualify (and WAIT until mid January) use one of the IRS FREE File programs ... last year your AGI just had to be $73K or less ...
Free File: Do your Federal Taxes for Free | Internal Revenue Service
