The best way is to forfeit your commission as then you are not required to pay taxes on the income and use it toward closing costs 

Have her sign a contract indicating the amount settles all claims and that she forfeits any future claims against you.

I've seen it where 60 days notice is required, tenant pays full amount for the month they terminate in and forfeits their deposit. 

Lastly, courts have ruled that if the landlord fails to return the deposit and/or an itemized statement within the required 21 days, then the landlord forfeits the right to deduct anything and must return the entire security deposit.

I also mentioned that the listing agent said cash only and inquired if that meant that we literally have to have cash or of they would entertain financed offers without a "finance contingency" meaning we would forfeit earnest money if financing fell through.

Hill and nine co-defendants — brokers, appraisers, lawyers and recruiters to the scheme — were found guilty on a combined 436 counts ranging from mail, loan and wire fraud to money laundering.

Is that something that you return to them or do they forfeit the security deposit?

If they don’t move in, they forfeit the fee since I have to re-list.

This deposit would be forfeited if they decided to not purchase the house at the end of the 12 month term.

In my lease, I state that they forfeit the security deposit if they cancel prior to moving in.