MEXICO CITY—The Mexican government expects to run up a fiscal deficit equivalent to 3.5% of gross domestic product for a second consecutive year in 2015, as increased investment at state companies is offset by a reduction in government operating costs.

Finance Minister Luis Videgaray presented the 4.6 trillion-peso ($354 billion) 2015 budget plan to Congress Friday. He said that while oil income is expected to fall on lower output and exports by state company Petróleos Mexicanos, non-oil tax revenue is projected to rise, reaching...