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 rate trouble after a money printing central bank which is capable of interest manipulation was created in 1951. Under a currency board (where no money printing was possible) the rupee was fixed from 1885 to 1951.It is not known why authorities target particular types of imports as hurting the exchange rate ignoring all other sections of the balance of payments.
Analysts say the targeting of individual imports is the most myopic of Mercantilist type of external trade imbalance analysis based on focusing on very small sections of the balance of payments and ignoring all other parts.
Those who believe single items cause exchange rate effectively ignore the rest of the trade account (as labeled by humans), the services account, the full current account and the capital account of the balance of payments.
Some who have a slightly expanded Mercantilist myopia, critics say, believe that the full merchandise trade account (the trade deficit) causes exchange rate trouble and ignore the service account (which may be in surplus), the full current account and the capital account.
Some take a broader view and believe that a current account deficit causes exchange rate trouble, but they ignore the capital account that has to be necessarily in surplus for a deficit to develop in the current account.
Analysts say the problem is compounded by conventional balance of payments reporting where central bank reserve account movements are considered 'below the line' and glossed over and is used as a balancing item.
In a credit driven fiat paper monetary system where gold as a domestic asset plays only a limited role, there are no 'balance of payments surpluses' as all monetary reserves are invested abroad.