Household Savings Rate : How do we measure up?

It is the last day of the month, and our only sources of monthly income, i.e. our paychecks hit our salary accounts today.  I had talked earlier about shooting for a 85% savings rate, and the need to be able to track this religiously, if we want to have any chance of hitting this super aggressive goal.  We have always struggled to come up with a system to track our expenses.  Either we get too ambitious and try to record every single penny we spend, and end up failing miserably in the attempt, or we become too lazy and forget to track any spending at all.  So we figured the first step was to come up with a simple way to monitor our overall monthly expenses and then refine the method if we see the need for it.  So instead of messing with tracking spreadsheets, notebooks, etc, my wife and I came up with this pretty simple method, that was staring us in the face.  Today, I simply added up my wife's and my monthly October paycheck, and I withdrew 10% of the amount in cash from our nearby ATM. 

We now have the entire month of November to eke out, using just the cash we have in hand.  We purposely chose to limit the cash withdrawal to 10%, so that we have a 5% buffer in case we needed the extra expenditure to finish up the month.  We intend to cover all our monthly expenses by drawing down from this kitty and paying in cash for all our spending.  There are a few expenses that are paid in auto-pilot mode through online websites such as utilities and phone-bills.  We will simply draw out an equivalent amount of cash from our 10% stock and keep it aside to ensure that we stay true to our target spending allocation. 

To summarize, we will only spend the "real world" money that I withdrew from the ATM in hard cash (which is 10% of our joint monthly income) and will leave all of the remaining online wealth (in bank accounts, SIPs, home loan EMIs, insurance payments, etc) to remain as investments. 

I suggest this method to you as well, as it should be pretty simple, and reduces the burden of thinking about it.  The one thing that will not be covered by this method, is tracking where our expenses are actually going into (for example how much are we spending on food, utilities, entertainment, health care, school fees etc) However, for starters if we can stick to the 15% spending target, I don't think there will be much need to figure out where we spent it.  It is only if we are consistently over-spending beyond the 15% target, will we need to spending distribution, so we can figure out where to cut back.  But then, we will cross that bridge when we come to it.  For now, on towards a frugal November!