If you wish to make a lump sum offer to pay off an IVA then you can do that. You usually need to make an offer of as close to the original dividend as possible and make it known to the IP that the money is there just for a full and final.
Where would the money be coming from?
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
If the money is yours, you are liable for the full original debt plus fees.
If however you are being gifted the money by a third party, you could offer a sum to make the total amount paid into the IVA close to the agreed dividend. You have to make it clear that the money is being offered only for a Full and Final, and if not accepted the money will not be available.