Hello,
Our PTO has an audit committee made up of two or three parents who volunteered to be on the audit committee.
I was part of the first audit committee, which began several years ago because the new treasurer at the time knew it was something the PTO should have. Actually, it was at my first PTO meeting ever, and the Treasurer made a motion to form an audit committee. Later I found out she hadn't told the president she was going to make the motion, because she knew the president would shoot down the idea if she knew about it in advance. I seconded the motion (I had been involved in a co-op preschool board and had a little bit of background about why it is important to have regular audits). Once the motion was approved, the President snottily asked who would volunteer to be on the committee, and that's how I got sucked in to our PTO LOL!
The reason I bring up the history is to help explain how our audit process works. At our first meeting, our intention was to audit the prior year. However, this would have been very difficult, because up until then, there weren't very formal processes for keeping a good paper trail when it came to check requests. The new treasurer wanted to implement some better processes. So, as a committee we decided our efforts would be better focused on helping the treasurer set up some new procedures. We met monthly to audit the prior month and make recommendations to the treasurer. As time went on, the meetings decreased to bi-monthly or quarterly. Now I am the Treasurer and I try to meet bi-monthly. I like meeting frequently, because that helps me keep things in order, and I don't let the paperwork get out of control. I know I need to have everything together for the audit commitee. When I need people to fill out forms, I can blame it on the audit committee :o)
Our audit commitee looks at all the checks written; makes sure there is a Check Request form filled out with proper documentation; makes sure each check request form and each check are signed by two check signers; makes sure that each expenditure was approved, either in the beginning-of-year budget, or by special vote; makes sure the checkbook register (or general ledger) matches the bank statement; makes sure all checks are accounted for; checks the mathematical accuracy of the checkbook register; makes sure the ending balances of the checkbook register and bank statement match; makes sure cash deposits were counted by two people; checks to make sure that all transactions are posted to the proper budget category, etc. Ideally, they should be able to do a spot check on most of these items, but usually they end up going through every transaction for the month. Because they meet fairly often, it is not that overwhelming.
When I was part of the coop preschool, we had an annual audit done and we hired someone for that.
Hope that helps!