Robert Chote testified before a parliamentary committee that immigration is a net plus for Britain's finances, the Financial Times reported.
Most migrants who come to Britain arrive "after some other country has picked up the expense of educating them, and in some cases, not all cases, they will then leave the country before they get to the point at which they're most expensive, in terms of pension and healthcare," Chote said.
Prime Minister David Cameron's government has pledged to reduce net migration to no more than 100,000 a year. A large influx of immigrants from Poland and other eastern European countries has fueled concern.
The OBR said in July that holding net migration to 100,000 would mean government debt would balloon compared to GDP if other things remained the same. In the year ending June 30, 2013, net migration was 182,000, the first increase in two years.
Ion Jinga, the Romanian ambassador to Britain, said Tuesday few immigrants from his country have appeared to have come to Britain since restrictions on Romanians and Bulgarians were lifted Jan. 1, the Daily Express reported. While he said exact figures are hard to come by since immigrants are not required to register with police in Britain, he believed fewer than 25 have come from Romania in the first two weeks.