In simple terms you can say that acquisition is an act of one company taking over or acquiring another company's controlling interest. This can be done either by buying assets of that company or buying shares or stocks of the company.
Special Allocation Rules For Certain Asset Acquisitions. the gain or loss of the transferor with respect to such acquisition, the consideration received for such assets shall be allocated among such assets acquired in such acquisition in the same manner as amounts are allocated to assets under section 338(b)(5).
The seller usually seeks to maximize amounts allocated to assets that will result in capital gains tax while minimizing amounts allocated to assets that will result in ordinary income taxes.
A penalty may be imposed for failure to file Form 8804 when due (including extensions). The penalty for not filing Form 8804 when due is usually 5% of the unpaid tax for each month or part of a month the return is late, but not more than 25% of the unpaid tax.