You can be Toraso Umnaso even if you have a job.
Shulchan Aruch (Y.D 243:2)
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See also Shach (C.M. 124:4)
The above is referring to stam Toraso Umnaso. However there is a higher level of Toraso Umnaso in regards to being patur from Tefila:
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However see the Mishna Berura (146:9) quoting the Elya Rabba that in regards to learning during krias hatorah (about which there is an opinion that someone who is Toraso Umnaso is permitted to learn):
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