You will receive a Form 1099-R reporting the retirement-account distributions paid to you. You must report the Form 1099-R on your tax return and the taxable amount will be included in your income.
(I assume that you have notified the custodian or administrator of your father's death, which you must do, and the payments made after your father's death are being paid to you, not to your father. As beneficiary, the retirement account became maintained for your benefit immediately upon his death.)
You will receive a Form 1099-R reporting the retirement-account distributions paid to you. You must report the Form 1099-R on your tax return and the taxable amount will be included in your income.
(I assume that you have notified the custodian or administrator of your father's death, which you must do, and the payments made after your father's death are being paid to you, not to your father. As beneficiary, the retirement account became maintained for your benefit immediately upon his death.)
While the above answer is completely true, it may also help to know exactly what kind of retirement account this is. You may have options and responsibilities more than just cashing a monthly check. (For example, is it a defined benefit pension, an IRA, a 401(k), a 403b, or something else?)