Project planning and spreadsheets are two topics you could study that are related to budgeting. You could also study project management and business finance to support the information you learn from your budget studies. You could choose to learn specific budgeting software programs, such as Libre Calc. You could also study business writing, communications skills, or presentation skills and software programs like PowerPoint in coordination with your budget studies. Accounting courses, such as how to do receivables and payables, could also be helpful topics for you to learn along with budgeting if you decide to make this field part of your career.