Form 1040 line 4a or 5a should show the entire gross amount of the distribution but only, if the option to spread the income over 3 years is chosen, only 1/3 of the taxable amount of the distribution should appear on line 4b or 5b. Only the amounts on lines 4b and 5b affect the rest of your tax return.
However, if you chose to include the entire taxable amount on your 2020 tax return instead of spreading it in equal parts over 3 years, the entire taxable amount of the distribution will appear on line 4b or 5b.
If you repaid some or all of the distribution, you indicate that during the Form 1099-R and on Form 8915-E that is subtracted from the portion (all or 1/3) you otherwise chose to include on your 2020 tax return.
