Why is HMRC introducing RTI?

HMRC is introducing RTI in order to modernise the Pay As You Earn (PAYE) system and keep pace with changes to modern working patterns. Nowadays, many people have more than one job, and can change jobs more frequently. This means people sometimes pay the wrong amount of tax. RTI provides HMRC with up to date information, so it should be easier to ensure deductions for tax, National Insurance and student loans are accurate.