401(k) excess profit sharing contributions

[Guest paytaxesforusa]

Employer of single owner-employee corporation mistakenly contributed $4000 excess profit sharing contribution in excess of the limits (25% of salary). Noticed mistake on Dec 28th the same year. Question: (a) Must form 5330 be filed if excess contribution is returned to employer before year end? (b) Section 4972 ( c ) (1) (A) (for the current year) surprisingly does not have a provision as in ( c ) (1) (B) (i), does this mean contribution returned to emplyer can only 'compensate' overcontribution from previous year but not from the current year?? ( c ) Section 4972 ( c ) (3) on the other hand seems to imply that employer's excess contribution can be returned without penalty until employer's tax filing date for the year in question? But only if the overcontribution was due to a 'mistake of fact'? This is not mentioned at all on form 5330.

Is there a short answer: File form 5330 or not? Penalty or not?

Thanks for clarification!

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