Expense-sharing calculation
Comments

Inline commend are usually no JavaDoc comment (/* vs /**).
Please check your comments, if they add any new information, that is not covered by the method or variables names, e.g:

    /**
     * If the payer is beneficiary remove the payer from the list of
     * beneficiaries
     */

    if (IfPayerIsBenificiary) {

        consolidatedBenificiary.remove(payer);
    }


could be a oneliner to improve (opinion!) readability:

  if (ifPayerIsBenificiary) consolidatedBenificiary.remove(payer);


As mentioned by the other reviewers, and I can only stress this point: comments are not used to explain what you are doing but why.

Variables/Method

Variables starts lower case in java.

In java it is not that common to define/initialize variables at the beginning of the method. Just do it when you need them. (e.g amountToBePaid)

Naming a method getPayDetails and return void is confusing. Just call it print...

Generics

List&lt;String&gt; benificiaryList = new ArrayList&lt;String&gt;();


Since Java 7 you can omit the second &lt;String&gt; and use the diamond operator &lt;&gt;

Simplification

checkIfPayerIsBenificiary could be written as:

public boolean checkIfPayerIsBenificiary(String payer, List&lt;String&gt; beneficiary)
{
    return beneficiary.contains(payer);
}


If this don't need to be public, just inline the one usage. Your variables is telling everything IfPayerIsBenificiary in that place.

Unused code

setPayableOrToBePayed and outputMap are not used. If there is no code missing in your question, just delete it.

consolidatedBenificiary is redundant and can be inlined.

(to be continued after you completed your code)