Kirk has indicated previously that he'd return to work next month but hadn't specified a date. The Republican's spokeswoman, Erin Athas, confirmed the date on Thursday. She had no further details.
The 53-year-old Kirk suffered a stroke last year which limited movement on the left side of his body. He's undergone rehabilitation for his movement and speech.
Kirk has been releasing video updates on his progress including footage of him working with therapists and climbing stairs.
Kirk discussed his plans with reporters while voting in suburban Chicago last month, not long after he participated in a charity stair climb at the Willis Tower.
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