If you sell SaaS subscriptions on behalf of vendors — as a reseller, MSP, or agency — you've almost certainly run into coterm quoting. A customer wants to add 10 more seats or a new module halfway through their contract, and suddenly you're in a spreadsheet counting days, dividing by 365, and hoping the tax line still ties out.

This guide walks through what co-termination is, why it matters for subscription businesses, and how modern CPQ software for SaaS eliminates the manual math entirely.

What is coterm quoting?

Coterm — short for co-termination — is the practice of aligning every product line on a quote to a single contract end date. When a customer expands mid-term, the new line item is prorated so it expires alongside the original subscription instead of running on its own renewal cycle.

The alternative — letting every add-on run its own 12-month term — creates a mess: a customer with five products can end up with five different renewal dates, five invoices, and five awkward conversations per year.

The coterm math, in one formula

The proration calculation itself is simple:

prorated_price = annual_price × (days_remaining / 365)

Example: a $1,200/year product added with 90 days left on the contract prorates to $1,200 × (90 / 365) = $295.89.

The math is easy for one line. It gets painful when you're quoting 15 SKUs across three vendors, some annual, some monthly-billed-annually, some with tiered volume discounts. Do it by hand and you'll ship a wrong quote about once a month. Learn more about how automatic coterm proration works inside Sasquote.

Why coterm matters for SaaS resellers and MSPs

Clean renewals. One date to negotiate, one PO to chase, one invoice per customer per year.
Faster expansion sales. Add-ons become a one-click sale instead of a 20-minute exercise in Excel.
Fewer billing disputes. Customers see the exact days-remaining math on every line, so nothing feels like a surprise.
Better forecasting. Aligned contracts make ARR reporting and renewal pipeline visibility trivial.

The four common coterm scenarios

1. Mid-term seat expansion

Customer bought 25 seats in January and wants 10 more in August. Coterm the new seats to the December renewal date — prorate for the ~5 months remaining.

2. Adding a new product line

Customer already has Product A on an annual term. They add Product B midway through. Both products should renew together next year.

3. Multi-vendor bundles

MSPs bundling Microsoft, security, and backup products need every line to hit a single renewal so procurement isn't slammed with rolling invoices.

4. Acquisition or consolidation

A customer acquires another company mid-term and wants to fold the acquired subscriptions into their existing contract. Every line reprices to the master end date.

How to run coterm quoting in Sasquote

Open the Quote Builder and pick a client.
Set the target contract end date on the client profile.
Add products from your catalog — Sasquote reprices each line automatically.
Send the quote, track opens, and convert to a signed order.

If you're an MSP evaluating tooling for this workflow, our quoting software for MSPs page has a side-by-side of how Sasquote replaces spreadsheets and legacy CPQ suites.

When coterm isn't the right call

Occasionally a customer prefers to keep a new product on its own renewal — usually because it's owned by a different budget or department. Sasquote lets you skip proration on any line, so coterm is a default, not a lock-in.

Ready to stop hand-calculating proration?

Sasquote does coterm math on every line, every quote, automatically. See pricing or start today — you can send your first coterm quote in under 10 minutes.