Hi Steph and welcome to the forum
That will depend on exactly what your IP wants. They should normally write to you about a month before the review is done to advise you of their requirement.
In my office we generally ask for the following:-
1 Last 3 months wageslips
2 Most recent P60
3 Most recent accounts and tax return (if you are self-employed)
4 New income and expenditure account (a form is provided for this including last year's figures)
5 Written confirmation that you have not received any windfalls during the year.
Also if there have been any material differences in any of your expenditure, then documentary evidence of this may also be required.
Good luck with the review.
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