I filed jointly the past two years but did not include the my spouses foreign earned wages, roughly $15,600 per year. Can I add those earning onto this years filing?

[joesabia24]

We both lived in the US when these monies were earned. The employer is based in the UK. UK taxes have not been deducted from these earning. We do not have any “w-2 like” documentation. We do have monthly paystubs.

[DavidD66]

No, you cannot add prior year income to your current year tax return.  You will have to file amended returns to report the income.  You do not need a W-2.  Once you have started your amended return, 

• Search for foreign income.
• Select the Jump to link in the search results.
• Answer Yes to Did You Make Any Money Outside the United States? and follow the onscreen instructions.

For information on how to amend your returns see:  How do I amend my federal tax return for a prior year?

[joesabia24]

Do you think I will pay fees and/or penalties on these earning. They were roughly 16K per year?

[Vanessa A]

Yes, you will likely have to pay a late penalty and fees for underreporting income for the past 2 years. 

"The amount of an accuracy-related penalty equals 20 percent of the portion of the underpayment attributable to the taxpayer’s negligence or disregard of rules or regulations or to a substantial understatement.3  The IRS may assess penalties under both IRC § 6662(b)(1) and IRC § 6662(b)(2), but the total penalty rate cannot exceed 20 percent" IRS Underreporting Penalty

You can contact the IRS to see if you can get some or all of the penalty waived through an abatement or administrative waiver.