No. Just as the Referendum result didn’t stop or change anything, nor does triggering Article 50; it’s only by finishing Article 50 that you get change taking place. Article 50 is not an end, it’s a process for leaving the EU. The principle is that until you’ve left you remain a member state, and as long as the UK is a member state – so until it’s finished Article 50 – it is liable for paying budgetary contributions, it’s liable to rulings by the European Court of Justice in relevant areas, and EU laws have the same effect they do now.
Do we need to repeal a law to stop payments? No, because the payments the UK makes to the EU are bound up with the payments that member states are required to make. The UK could pass a law saying it’s not sending any more money to the EU but it would then be in breach of its obligations. If you’re trying to negotiate a good deal for exit then that’s probably not going to endear you to the other countries. There’s another question about what kind of deal you have with the remaining states in the EU afterwards, but until Article 50 is finished the UK has just the same obligations as all of them.
Read more of Simon Underwood’s Brexit commentary here.