Beginning November 1st, Amazon will collect Massachusetts sales tax on online purchases. This is the result of a negotiated agreement with the Massachusetts Department of Revenue (MDOR) last year. The MDOR reasons that Amazon’s opening of an office in Cambridge and their acquisition of North Reading robotics start up, Kiva Systems in 2012 constitutes a “substantial presence” in Massachusetts. MDOR expects to collect approximately $37 million annually from Amazon as a result. However, this arrangement is exclusive to Amazon—other online retailers are not necessarily obliged to collect Massachusetts sales tax.