Generally, if you are generating revenues that equal half the cost of a new employee (and remember, that cost should include additional benefits and package costs), you can go ahead and hire. Typically that new hire should generate a return for you -- both in actual ROI and in terms of relieving you of certain tasks and duties.

In terms of your tax exposure, you would need to consult with your tax preparer or advisor. A lot of factors can enter into the final tax obligation, depending on your particular circumstances.

Again, remember to include all costs, as that $40,000 per year employee will really cost you more like $50,000 to $60,000 depending on where you are and what kinds of benefits you are offering (or willing to offer).

That said, the idea of saving a wage over time can end up costing you a fortune in terms of leveraging your own time and effort in your own company.