Tax Calculation question (Tax Return)

Nixter · 3 May 2007 at 10:21PM

Last year I was self employed for a while.
This is the first time I have to fill in my tax return and I've decided to do it without the help of any accountant.
One question about the automatic Tax Calculation on the online self assessment page:

2006-07 balancing payment                                          £ 5,726.62 
1st payment on account for 2007-08 due 31 January 2008
(Note: 2nd payment of £ 2,863.31 due 31 July 2008)                 £ 2,863.31 

Total Due by 31 January 2008                                       £ 8,589.93

What does the 2007-2008 payment on account mean?
Is this is an estimated or actual figure that HM Revenue&Customs wants me to pay up front?
I don't really understand this as I thought I would only be providing figures for the 2006-2007 tax year and I'm pretty sure my tax liability will be much lower next tax year as I'm now back as a normal employee, paying through my PAYE code.

Many thanks