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You should have the institution where you will have or already have the IRA do a transfer on the portion you wish to place in the IRA. If you do that you will only pay tax on the half of the portion you keep. If you keep out half you will be taxed on just that portion and it will be added to your other income. How much you will pay in tax will depend on how much your total income is with the half of the 401K added.
If you have no other income than the half of the 401K you would pay no tax because the amount is much lower than your standard deduction and exemption amounts.
If you do receive the distribution directly make sure you put half in the IRA before 60 days are up or you will pay tax on the entire amount. But again if that is your only income you actually will owe no tax and if the 401K withholds the traditional 20% (as they m=normally do when issuing directly to the employee) you will file and get that all back. If you have other income the $5100 will be added to the income and taxed at your normal rate.
Let me know if you need clarification on all that above