Today's Tightwad Tuesday is a very basic how-to that I use all the time, but I have found that a lot of people don't know how to handle.  It is Dave Ramsey's tool on how to handle irregular income.  You know, the not-always-the-same-in-your-paycheck, commission, extra money, tax refund, "stimulus check" type money that flows into and out of our bank accounts with such lightning speed that it leaves us shaking our heads and saying, "huh?  Where'd it go?  Where'd it go?" in utter amazement.  Nearly all of us will be getting some irregular income sometime soon, and there are many people who have 100% irregular income, like if you own your own business or are on 100% commission and your income is variable. 
So, here's what you do.  You use the regular budget (a zero based budget that spends out everything you know you are getting in your check or the minimum you always get if you are somewhat variable on the amount) to allocate the "certain" money.  You just make that go as far as it can go.  So, for example, let's say my husband's regular check is $2000.  I list my tithe of $200, my savings of $200 and my mortgage at $1000.  I have $600 left, so I keep going.  I am going to put $200 to utilities, $200 for groceries, and $200 for gas for the car.  That is all I can do, because I have spent out the full $2000.  But, there are lots of things that I need/want/desire to do that I have not paid for with the $2000.  So I take out another sheet and list them, with amounts... more grocery money, $100.  More gas money, $100.  Clothing, $50.  Tuition for co-op, $150.  Car insurance, $375.  Vacation to Disney, $5000.  Notice I am putting down everything I would LIKE to do, not just what I need to do.  Now I put in in order of priority.  (I keep saying "I" but I mean "we"... you will need to call a budget committee meeting with both spouses to do this and agree on items and their priority.)  So, mine is 1.  Car insurance, $375 (Due this month, can't drive without it.)  2.  Clothing, $50 (Have to pay for the dance costumes before end of April).  3.  Co-Op tuition, $150 (want to go next year and reg. due now)  4.  More grocery money, $100.  5.  More gas money, $100 and  6.  Disney (a total dream at this point!), $5000.

Now, when I get my extra money, here's how it works.  Let's say I sell something on eBay for $75.  I look at the list.  The first item, car insurance, is $375.  So I hold on to that $75 and put it in my account or envleope and mark it "car insurance".  Next, My husband's pizza tips for a weekend were really great, and he brought home $300.  Guess what?  Car insurance is funded!  I go ahead and pay it.  Then the stimulus check arrives, $2100.   That is gonna do a lot here!  Instead of just deciding what to do with it on the fly, I now have a plan!  I pay the $50 clothing, the tuition $150, the grocery $100, the gas $100, and I still have $1700 to put towards Disney!  (It is now feeling like it may actually happen someday!)

So, although your items will be different, and mine are too (Disney has never made the cut!  LOL!), you can see how it works.  Hope that helps someone!