A sales territory is the slice of the market a rep is responsible for, drawn by geography, industry, account size or a named list. It decides which deals a rep is allowed to work, so it sets the ceiling on their earnings before the commission plan gets a say in anything.
Territory design is filed under operations and treated as a mapping exercise, which badly undersells it. Drawing the boundaries is the single largest pay decision a company makes, and it is made months before anyone writes a rate into a plan. Give one rep the account list with three expanding enterprises on it and another the same headcount of accounts in a shrinking category, then put both on the same plan, and the plan will faithfully pay one of them twice as much for identical work.
Territories come in four common shapes and most companies run a hybrid. Geographic boundaries are easy to explain and easy to enforce, which is why field sales and payments channels still use them. Vertical territories trade that simplicity for expertise. Segment territories split by company size, which usually means splitting the sales motion too. Named-account lists abandon boundaries entirely and hand each rep a specific set of logos, which is the cleanest for crediting and the most work to maintain, because somebody has to decide where every new company in the market lands.
The number to look at when judging a territory is quota coverage: the addressable opportunity inside the boundary divided by the quota assigned to it. Planners commonly aim for something in the region of three to five times, and that is a rule of thumb across the profession rather than a measured finding. What matters is comparing it across the team. A territory at 1.2 times coverage will produce an underperforming rep who is in fact working harder than the colleague sitting at 4 times, and the attainment report will not say so.
Two reps carry the same $900,000 annual quota on the same commission rate. Their territories were drawn by headcount of accounts rather than by opportunity.
Rep B has to close more than four fifths of everything available to reach the same number Rep A reaches at a third. No commission rate fixes that, and no amount of coaching does either. The correction is a different quota or a different boundary.
Territories get redrawn when a company adds headcount, and the redraw usually lands with an effective date and no transition rule. A rep who spent five months working an account watches it move to a colleague in April and close in June. Whether they are paid on it depends on a policy that, in most companies, is invented in the week the first complaint arrives. Write the rule before the redraw: name a window during which the previous owner keeps credit on deals already in a late stage, and put it in the plan document rather than in an email from the VP.
The long form lives in the guides: Plan templates.
Commish pays sales territory the way your plan describes it, shows the arithmetic on every line, and traces each payment back to the deal that earned it.