When was IR35 Introduced?

The press release ‘IR35' was issued on 23 September 1999 as part of the pre-budget announcements for the April 2000 budget from the Treasury. The actual legislation came into force on 6th April 2000 as part of the Finance Act 2000.

Following the introduction of the legislation, all contracts since 6th April 2000 could be covered by IR35, meaning that HMRC can continue to investigate contracts dating back to the introduction. Contractors may be liable for back taxes.

Past contracts that would have fallen under IR35 and are deemed to do so by an inspector of HMRC will attract additional tax and NIC liabilities that the contractor may have to pay now, or in the future.  The potential back tax can be significant and run into tens of thousands of pounds.