Sri Lanka has since raised taxes on motor vehicles, and new tax reforms are also taking effect.
Non-tax revenues fell 4.1 percent to 35.1 billion rupees, down from 36.6 billion rupees a year earlier.
But current expenditure rose 10.2 percent to 360.3 billion rupees, growing faster than a projected 8.5 percent for the year.This left a yawning revenue deficit of 75.4 billion rupees, higher than the 53.4 billion rupees projected for the whole year.
A revenue deficit or a gap in the current account of the budget indicates that the state has to borrow for day to day running, and the entire capital investment has to be financed from debt.
The budget for 2011 expected the revenue deficit to be brought down to 53.4 billion rupees from 118.8 billion rupees a year earlier. But in the first four months of last year the revenue gap was higher at 86.3 billion rupees.
The state capital spending was 98.2 billion rupees up 17.2 percent from a year earlier, in line with budget projections.
This left a budget deficit of 173.6 billion rupees before grant funding of 2.7 billion rupees and 170.9 billion rupees after grants, a gap of about 2.7 percent of gross domestic product.
If current trends continue the annual deficit would be around 8.0 percent of GDP, higher than the projected 6.8 percent.
Data also showed that the debt stock, which is an indirect way of measuring the budget gap, expanded 211 billion rupees in the first four months.