A proof of interest is similar to a proof of claim, i.e. proof that the filer is a creditor of the debtor. As such, a proof of interest is generally subject to the same rules as a proof of claim is. There is no need for an equity security holder to file a proof of interest if
the interest is properly characterized on the debtor’s schedules and is certain and for a set amount (i.e., non-contingent and liquidated). If a security interest does not fulfill the three requirements outlined above, the holder of the security interest must file a proof of interest, which will trump the debtor’s characterization of that interest.