Typically, Form 4667 is used for audits of the Federal Unemployment tax (Form 940) for businesses. This is a proposal, not a decision. Although this tax doesn't subject the owners of the business to liability, it can be serious - mainly because of the enormous penalties imposed by the IRS.
So, if the business dissolves, the tax will not be imposed on the owners. But, if the business remains on-going it becomes urgent to fight this tax.
Respond to Form 4667
First, you must determine upon what basis the IRS is making this proposal. Sometimes, the IRS has misapplied payments or has not received returns. So, first call the IRS agent on the notice and request the "Wage & Income Transcripts" & the "Account Transcripts" for the account so you can compare them with your records.
Next, get copies of all payments and match them with the Forms 940. If the problem is identifiable, it can usually be resolved with an account adjustment or amended returns.