Gather some information. You need to know if you are filing single or married, how many dependents, estimated income and estimated taxes paid.
Access the H&R Block calculator (see Resources). Enter whether you are filing single or married, then your age at the end of the year, number of dependents, their ages and if they are students.
Enter your estimated wages, then your estimated taxes at the end of the year. You are then ready to add income from any other sources such as interest, stocks, self-employment income or Social Security.
Estimate tax-deductible expenses. Fill out how much you will spend in state taxes, real estate taxes, mortgage interest and charitable deductions. You will also estimate job expenses, student loan interest and tuition and childcare expenses. Click "Calculate" and the system will reveal how much money you will get back or how much you will owe.