Letter 98C is used by the IRS to detail how they say that mistakes were made by you in returns which were filed for your business.
When multiple periods are in dispute, the IRS often takes money from one period and applies it to another period. This may be the reason that a discrepancy has occurred. It's best to get the Account Transcripts for ALL time periods to compare with the business records. You probably should get the Income documents as well so you can see the IRS file & check it against your records.
It is important to gather this information for all tax periods at issue and simultaneously review the business records so you can resolve the account before major problems occur. The amount of penalty & interest charged by the IRS can harm a business, perhaps drive it to close its doors.
In the future, you can designate on voluntary payments you make to the IRS which time period you want to apply the payments. This will prevent the IRS from misapplying your payments to the wrong time period.
Please follow the Business Tax Prep Steps & contact the attorney at TaxHelpLaw so we may construct an Action Plan for you to confront the IRS!