Yes. You need to include the income from your seasonal job along with your regular earnings.
The following is taken from IRS Pub. 525 Taxable and
Nontaxable Income:
"In most cases, you must include in gross income everything you receive in payment for
personal services. In addition to wages, salaries, commissions, fees, and tips, this includes other forms of compensation such as fringe
benefits and stock options.
You should receive a Form W2 from your
employer or former employer showing the pay
you received for your services. Include all your
pay on line 7 of Form 1040 or Form 1040A or on
line 1 of Form 1040EZ, even if you don’t receive
Form W2, or you receive a Form W2 that
doesn’t include all pay that should be included
on the Form W2."
