If you’re a resident of Philadelphia with unearned income, you must file and pay the School Income Tax (SIT) every year.

Unearned income includes dividends from stocks, interest from corporate bonds, and more. SIT is due at the same time as your personal federal tax return, usually April 15.

Figuring out which sources of income are taxable for SIT—and which aren’t—can be tricky. You may want to seek the advice of a tax professional.

But if you decide to do it yourself, the video below will show you how to complete an SIT return, line-by-line.