Neville Goonewardene, who headed Sri Lanka's customs department, told a forum of importers that the agency was given a target of 570 billion rupees in revenue to collect.
He said the agency usually collected about 38 percent of the revenue in the first half of the year and 62 percent in the second.
But imports have begun to slow in the second half especially car imports, putting the agency behind the target.
Goonewardene said imports of cement, ceramics and steel was up.
Sri Lanka jacked up car taxes to discourage imports in February amid warnings from the both analysts and the International Monetary Fund that it would hurt revenue and singling out particular imports made no sense.
Then mostly so-called tax slashed permits given to members state workers were coming in.
Sri Lanka's rupee peg came under pressure from sterilized foreign exchange sales and manipulation of interest rates to finance bank credit driven energy subsidies.
Sri Lanka started having exchange rat