You will need to report 2015 wages earned on a 2015 Tax Return, you cannot combine tax years. You can try contacting your former Employer and they may be able to give you a copy of your 2015 Form W-2. If not, you can order a Transcript from the IRS that will show the details of your income for the year. Click here for a TurboTax FAQ which includes details on How to Order a Transcript from the IRS.
Whether or not you are required to file depends on how much your total income was during 2015. If you are Single or Married Filing Separately you would not need to file if you only had Wage income and it was below $6,300. However, if you had Federal Taxes taken out you still may want to file to get a refund. If you file as Head of Household for 2015 you would not need to file if you only had Wage income and it was below $9,250. And if you file Married Filing Joint you wouldn't need to file if your combined income was under $12,600.
