As you can guess, the government's main earnings are from taxes -- direct and indirect. However, the government doesn't earn only from taxes, it has other sources of revenue as well. Profits, dividends and telecom fees are some of the major sources of non-tax revenue.
The government also earns dividends from public sector undertakings (PSUs). It earns profits from PSUs by being a shareholder. Telecom licences and spectrum fees also yield revenue. Apart from this, another source of non-tax revenue is disinvestment and interest. Disinvestment in PSUs is a major non-tax revenue source. The government also gives loans to states from time to time. Interest on these loans gives additional revenues.
Royalty and other fees from companies on oil and gas blocks also form part of the revenue earned. It gets tuition fees at government-run schools and entry fees at museums and monuments. Charges from CGHS or Central Government Health scheme and related services also yield revenue.
All these sources together from the non-tax revenue stream for the government.

Watch the video by our Deputy Executive Editor, Gaurav Choudhury, for more insights on Budget 2019.