CoS Refernce Number

[syounusa]

Hi
Do you know how many digits the CoS reference number contains. My concern is in the tier2 application form there is 12 digit option but I received it as 11 digit from my employer. Is that something I dont need to worry about or it has to be exactly 12 digit unique number. And if it is 11 digit means 1 short so should I leave first digit blank or last digit.
Another question, my sponsor mentioned yes in Sponson Certifies Maintenance option in sponsor management system for applying my CoS. Does that mean I dont need to submit bank statement for maintenance and if not then will that cover my wife's maintenance as wel.
Any experience please share and a lot of thanks in advance.


Cheers

S