Let me attach come numbers to my earlier post about when I first switched to COBRA from my employer's group health plan.
For the first 6 months of 2007, I was paying $83.66 per biweekly paycheck, or 50% of the total premiums. My employer was paying the same amount, $83.66 per biweekly paycheck. Had I been working full-time, I would have been paying 25% of the premiums, or $41.83, while my employer would have been paying 75% of it, or $141.49.
When I switched to COBRA midyear, I became responsible for the entire premium. That premium per paycheck was $167.32. Convert that to a monthly premium makes it $362.53 ($167.32 x 26 / 12). Then add the 2% admin fee to get $369.78. That's what I paid per month for the rest of 2007.
In 2008, my employer got hit with a 6% increase, so my COBRA rate rose 6%, too, to $391.97. That's what I paid per month in 2008 until COBRA expired at the end of the year.
Another significant difference between paying COBRA versus being on my employer's plan was that I had to pay my COBRA premiums with after-tax dollars, not pretax dollars through payroll deduction. I went from paying half with pretax and the other half tax-free to paying all of it using after-tax dollars. My income was too high to be able to deduct my COBRA premiums (and the cutoff was only 7.5% of AGI back then).
Still, COBRA was a good deal for me. When I left COBRA at the end of 2008, I had to buy my own HI policy in 2009. I paid well over $400 per month (no dental) and those rates rose 50% in the next 2 years to nearly $700 per month. I ditched the policy and was underinsured for 2 1/2 years before the ACA exchanges arrived to rescue me.
I'd have gladly stayed on COBRA much longer than 18 months.