Self employed and inland revnue implication ?

As a company we have had sales staff on self employed basis we pay them a salary or a fixed amount for there monthly work like a wage however we do not pay employee ni... We have been trading for 2 yrs our turnover is 1mill however I know that these sales guys have not bothered to pay tax its not much as they only worked for a few months left us and joined another company on paye..so undeclaring this income.. What's likely going to happen, how will inland rev find out what's exposure for us for them how do they behave what can we do as a company to fix it...

Tell the Revenue. They will give you good advice about this
problem.

If you payed them an amount each month and they were self employed you were not liable for any ni payments. All you need to do is keep records of payments to them as this is classed as expenses on your business.Its up to them to declare what they have earned.Just have imformation if needed.

You are paying these people a salary and a wage so
it sounds to me as if these people are in fact your employees. If this is the case, you are liable to pay the tax and NIC on the amounts paid to the sales people. On top of this, you would be liable to interest and a possible penalty for not operating PAYE correctly. You cannot make someone self employed by just telling them that they are! It sounds as if you are very exposed should HMRC either decide to investigate your company or one of these sales people. If you want to fix it, I suggest you get your accountant to approach HMRC to regularise the position. If you come clean before they find out and co-operate fully, you will lessen the damage.
EDIT: James is muddying the waters by talking about CIS which is for the construction industry. It does not matter whether your workers have declared this money or not, it is still you who are liable if they are found to be employees. There was a tax case recently where the employer was required to pay the tax and NIC for a person they had treated as self employed, even though that person had paid his tax and NIC through self assessment.

Surely if your company is not involved with the CIS scheme where a main contractor must verify sub contractors with HM Customs & Revenue before any payments are made... no problem? As your sales people are sole traders and must be registered with HM Custom & Exicise to trade, its madatory to complete a annual tax return even if there only self employed for only part of the year. If they are on the system they will be sent a tax return form in which they will have to complete. If they were not registered with HM customs & Exicise and you was aware of this, your company could be breaking the law by paying a contractor by this method. If you only become aware of this when there contract expired i would inform HM customs & Reveue with the details to protect your company from future investigations.