The medical expense will presumably be tax free to you (as contractors and employees can be treated the same for a company plan).
If you have 140K of net income and no other income married joint with no dependents and no credits using standard deduction and two exemptions taxable income will be about 110,100.
Federal income tax estimate is 23,800.
In addition self employment tax of about 19800 is due on the net profit. For more details on this tax see http://www.irs.gov/taxtopics/tc554.html
Total federal tax about $43,600.
For 2013 federal rates please see http://www.forbes.com/sites/kellyphillipserb/2013/01/15/irs-announces-2013-tax-rates-standard-deduction-amounts-and-more/
Colorado state income tax using the same taxable income for Colorado as for federal of 110,100 at 4.63% rate is about $5,100.
Colorado rate is from http://www.colorado.gov/cms/forms/dor-tax/CY104EP.pdf
Rough estimate of net after taxes is 150,000 - 10000 expenses- 43,600 federal combined income and SE taxes - 5100 state income tax = 91,300.
If you have other income you can estimate about 20% for tax on that income (15% federal plus 4.63% state).
For example, if there is another 1200 per month x 12 months or about 15000 then that would be about 2250 added combined income tax.
Please ask if you need more discussion or clarification.