I'm currently fall under the foreign income exclusion and want to know how adding a 1099 income will affect this. Will I have to pay tax on both or just the 1099?

[1bezerra1]

The FEIE can be used to exclude income up to that amount. If your income is less you can deduct up to that amount. If the 1099 income is earned income you can include it and can claim the exclusion for the total foreign earned income.