applying for Tier 2 General - please help

[talktonight]

Hello everyone,

I'm switching from Tier 4 to Tier 2 General soon and I've got one question regarding the National Insurance.
It seems that it's necessary to provide NI number or say 'I don't have one' when applying for Tier 2 General.
So my problem is that I have NI number, however, I received some wages through it in 2013, even though my latest Tier 4 visa stated 'no work permitted'. I also received wages in the past 3 years using the same NI while being on other Tier 4 visas (with 20 hours per week allowance), however I always stated in the application forms that I don't have NI number (left the field blank) and never had my application refused or questioned because of that.
The question is, can UKBA run some checks on NI for Tier 2 General application or is it very unlikely?

Any advise would be greatly appreciated.