TurboTax will automatically list this form for you if you qualify. In order to qualify your AGI needs to be under $40,000 annually unless you are over age 70. If the program hasn't prompted you for this credit you may not qualify. Please see the link below for more information:
https://otr.cfo.dc.gov/sites/default/files/dc/sites/otr/publication/attachments/schedule_h_faq_01130...