Tax Code on Salary Slip

Hello,
I am due to apply for ILR next month and want to know if and how the tax we pay effects our application.
Last year while changing jobs I seem to have filled the P45 with information which ended up me being in the incorrect tax code. Now this resulted in me unknowling paying slighly less tax on my salary. This year from april onwards the Tax code was corrected and hence I am now paying the correct tax.
My question is that HM revenue and customs have not recovered that money for last year from me yet ( assume they will shortly!) is this something i need to sort out before applying?

Many tHanks.

Not necessary.

Thanks, So that means I need not worry about the tax that I have or have not paid as long as I have the salary proof.
kool.