Hi AM
What do the terms of your proposal say? It is usual to have to pay over 50% of any additional earnings by way of overtime, commissions and bonuses - but if you do not have that provision in your IVA the Supervisor may ask for you pay it all over.
If you have essential expenditure, this must be borne by the half you may be entitled to retain, and if not do submit a wish-list to your Supervisor who I would hope would see things on a reasonable basis.
I am afraid that general savings are not usually permitted during an IVA - if you have more disposable income then this should be requested by your Supervisor. Obviously if you have provisions for car and house maintenance, and miscellanous expenditure these should be saved until they are needed.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk