if there is no change in your tax liability there should be no penalties or interest. However, if your liability increases the penalties and interest increase each month. so waiting for the CP 2000 if it takes 2 years would cost you in penalties and interest about 30% of the additional tax 3 years about 40%. The %s are not exact and may be high because the interest rate changes. The penalty for late payment is .5% per month since 4/15/2023 (unless you're in California) interest is currently about 8% per year (about 0.022% per day compounded daily). if you are penalized you may be able to request abatement of penalties. Interest can not be abated.
