Union minister Arun Jaitley said today there was an increase of 18 per cent in direct taxes collection last year due to the Goods and Services Tax or GST and demonetisation. In the last four years of NDA government, there has been an increase of 1.5 per cent in overall taxes, the minister said. "The total tax base itself has increased significantly," Mr Jaitley said. "These are the changes taking place on account of GST implementation. As tax collection goes up, capacity to rationalise rates will increase. Therefore, that capacity to rationalise will increase total volume."