The TCS Treas 449 is usually a tax refund and the SSA Treas 310 is a 'normal' monthly SSA benefit. As far as I can tell, the 449 sometimes indicates that the refund did not come straight from the IRS, but might have been part of a tax offset program (i.e., they took something out to cover a debt you owed the govenment).
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I hear and I forget. I see and I remember. I do and I understand.--Confucius