It all depends on the taxpayer's circumstances.  For example, many of the taxpayer's assets will affect things.  The amount of their current/recent income also affects things.  So a taxpayer with a lot of usable assets and/or high income may not qualify at all.  But a taxpayer will few assets and low income could possibly qualify to waive most of it.

There are definitely nuances and strategies that can be used, so an expert in OICs can often get the best results.  But for the basic OIC, there are third party software providers that can walk you through everything.  One popular one is PitBullTax ($195 to buy it for one client).

But as I said, an expert can often get a better result by applying certain strategies.  For example, if I remember correctly, if the taxpayer uses any existing money/assets to pay off the State amount owed, that will allow a better Federal OIC because they have less money/assets.