Wish I had a dollar for every time some asked me this question. Will IRS Abate my Interest?
Let’s finds out what the IRS Code Section says about the issue.
The law requires the Internal Revenue Service to charge” interest” on any tax that is not paid by the return due date under Internal Revenue Code Section 6601. The IRS Restructuring and Reform Act of 1998, however, requires  the Internal Revenue Service to notify taxpayers of the proposed discrepancies of their tax returns within a 18 months of the original filing date in order to charge” normal interest”.  IRS has to adjust the interest charge if they make initial contact after that  period of time .
The federal law allows the Internal Revenue Service  to reduce or remove interest on tax increases attributable to errors or delays we made in the performance of ministerial acts (Tax Reform Act or 1986 – Ministerial Act provision).
The key question to be answered is what is a “ministerial act”. A ministerial is a procedural, mechanical, or processing act that does not involve the exercise of judgment and occurs even though you did everything we required you to do. If you believe you qualify for abatement of interest based on this provision, you should include your reasons in your response if you are trying to abate interest.
The law does not permit the Internal Revenue Service to reduce or remove interest for reasonable cause. Reasonable cause only applies to penalties and refers to an acceptable explanation of circumstances that prevented you from paying the tax when it was due.
The bottom line, unless you can prove that the IRS did something extraordinary to delay the processing of your case, you have a little chance of getting the abatement of interest. It is not that they do not wish to help, the law does not allow them to do otherwise.