A longitudinal study among 735 new TB cases was conducted from January 2015 through June 2016 in 10 woredas (districts) of southwestern Ethiopia. Between onset of illness and anti-TB treatment course, patients incurred a median of US$201.48. Of the total cost, the indirect and direct costs respectively constituted 70.6 and 29.4%. TB patients incurred a median of US$97.62 and US$93.75 during the pre- and post-diagnosis periods, respectively. Thus, patients incurred 53.6% of the total cost during the pre-diagnosis period. Direct out-of-pocket expenses during the pre- and post-diagnosis periods respectively amount to median of US$21.64 and US$35.02. Patient delay days, provider delay days, number of healthcare facilities visited until TB diagnosis, and TB diagnosis at private facilities independently predicted increased pre-diagnosis cost. Similarly, rural residence, hospitalization during anti-TB treatment, patient delay days, and provider delay days predicted increased post-diagnosis costs. TB patients incur substantial cost for care seeking and treatment despite “free service” for TB. Therefore, promoting early care seeking, decentralizing efficient diagnosis, and treatment services within reach of peoples, and introducing reimbursement system for direct costs can help minimize financial burden to the patient.