Employer suddenly tells me that I will receive a 1099 this year for my sales commissions. Is this legal?

Out of the blue today, my boss tells me that I will be receiving a 1099 for my sales commissions. I am a salaried employee and, from what I have read, this does not seem to be the proper way to do things. If I am not mistaken, commission should be paid via our payroll company and it is not appropriate for a salaried employee to receive both a W2 and 1099. Can anyone confirm? If it is legal, am I right to be perturbed that I'm just being told this 8.5 months into the year without having been given the opportunity to pay estimated taxes or put money aside? Advice is much appreciated! Thanks!