It matters in that amounts will not add up for the IRS. When they see your W-2 they will compare the amount you listed on Line 1., 1040. It would normally be entered on Line 8 Schedule 1 and then carry over to Line 7a, 1040.
It may not cause a problem. You may get a letter, but it is easy to explain the mistake. The important thing is that you entered all your income.
