Depends on what kinds of deductions you'd like to make. I'm sure there is some threshold as far as income goes as well, but a lot of times it does make sense to incorporate (or LLC) if you're making enough to offset the expenses involved.

Business or Hobby? Answer Has Implications for Deductions

I'm not an expert, but I've looked into it myself for my own business intentions. I'm not sure of the specifics surrounding retirement and incorporating.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth