While we rarely forget the mortgage, rent, utility, or grocery bills, there are some categories of expenses that many of us overlook. When you plan your budget, including an allowance for these occasional expenses will give you more room to maneuver financially in the future. The more accurately you foresee expenditures, the greater your financial flexibility. You’ll also experience less stress and frustration when an ‘unexpected’ cost comes up.

Some of the more commonly overlooked ways we spend money include vehicle maintenance, and medical costs. While we may have warranties and insurance plans, we sometimes forget to budget for the more routine aspects of these expense categories. For example, if you’re wise, you have a warranty which covers major engine problems, but have you budgeted for oil changes and fluid replacements? Similarly, we seldom forget to budget for health insurance, but we are likely to lose sight of costs like over-the-counter medication.

One way to integrate hard to remember expenses is to keep a budgeting journal. A simple memo book you keep with your financial documents will work; whenever an expense you didn’t plan for turns up, jot it down in your notebook. Every few months, read through and notice which expenses routinely surprised you.