For the whole of my adult life, I have been paid either once or twice a month. When Adam and I got married, his new job paid him every two weeks. This caused undue stress in my life, since I wasn't sure how to deal with the variable paycheck dates. Sometimes the first check of the month would be on the first. Other times, not until the 14th. While some bills can be put off a few days without too much problem, I've yet to find a landlord who allows rent to be two weeks late, several months a year.
I finally figured out a workable system. Rather than simply budgeting the whole month, I took a look at the billing cycle for each bill. Those due between the 1st and 15th would be paid from the second check (of the month before). The bills due between the 16th and 31st are paid from the first check. All the rest could go into either check, as funds allowed.
Then I wrote up our income and expenses by paycheck. For example, our first paycheck of the month includes expenses for groceries, gas, household utilities, and credit card payments. The second paycheck covers rent and investments.
Twice a year, we get that bonus three-paycheck month. If you make enough money that you can cover your budget with the first two paychecks, the third can simply be savings, investment, funding for special charity projects or whatever else you like. However, for the rest of us, I've found that the third paycheck tends to budget nicely for those non-monthly expenses, such as car registration and insurance, quarterly taxes, and so forth.
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