--- title: "SaaS subscriptions: how the model works and how to manage one" description: "How a SaaS subscription bills, renews and changes mid-cycle, with annual-discount and proration math, and what subscription billing software does for you." canonical: "https://saascron.com/saas-subscription/" language: "en-US" author: "Ricardo Machado" author_url: "https://saascron.com/author/ricardo-machado/" published: "2026-10-20T12:00:00-04:00" updated: "2026-10-20T12:00:00-04:00" category: "Metrics & Pricing" tags: ["Subscriptions", "Billing", "Recurring revenue", "Proration"] --- # SaaS subscriptions: how the model works and how to manage one > How a SaaS subscription bills, renews and changes mid-cycle, with annual-discount and proration math, and what subscription billing software does for you. Your product has paying customers, and the billing questions have started. One customer wants to upgrade halfway through the month, another wants an annual plan, and a third asks why the invoice shows a credit and a charge on the same day. Each one is a subscription question, and your answers need rules you can repeat. A SaaS subscription is an agreement in which a customer pays a recurring fee, monthly or yearly, for continued access to software that the vendor hosts and runs. This guide covers how the model works, the arithmetic of discounts and mid-cycle changes, and what a billing system does for you. If SaaS itself is new to you, start with [What is SaaS?](https://saascron.com/what-is-saas/). ## A subscription in plain terms Think of a magazine subscription. You pay for a year up front or one month at a time. Issues keep arriving until you stop paying. If you switch to the premium edition halfway through the year, the publisher credits the issues you had not received yet and charges you for the rest of the premium year. A SaaS subscription works the same way, with software access in place of issues. Five terms carry most of the weight: - **Billing period:** the stretch of time one payment covers, usually a month or a year. - **Renewal:** the automatic start of the next billing period, with a new charge, unless the customer cancels. - **Proration:** charging or crediting only the share of a period that a change affects. - **MRR (monthly recurring revenue):** the monthly value of all active subscriptions. An annual plan counts as one twelfth of its price each month. - **Dunning:** the process of retrying a failed payment and reminding the customer before access ends. ## The life of a subscription, step by step 1. **Sign-up.** The customer picks a plan and a billing period. A trial may come first. 2. **First invoice.** In the usual setup, the fixed fee is charged at the start of the period it covers. 3. **Renewal.** At the end of the period, the next invoice is created and charged automatically. 4. **Change.** The customer adds seats, upgrades or downgrades. The billing system prorates. 5. **Failed payment.** A card expires or is declined. Dunning retries the charge and emails the customer. 6. **Cancellation.** Access ends now or at the end of the paid period, depending on your terms. Every step changes either the invoice, the MRR or both. The table below shows how, and it is the reference to keep next to your finance reports. | Event | What happens to the invoice | What happens to MRR | |---|---|---| | New monthly subscription at $50 | $50 charged now | +$50 | | New annual subscription at $480 | $480 charged now | +$40 ($480 / 12) | | Upgrade from $50 to $80 mid-month | Credit for unused $50 time, charge for remaining $80 time | +$30 from the change | | Downgrade from $80 to $50 mid-month | Credit for unused $80 time, usually not refunded in cash | -$30 from the change | | Failed renewal payment | Invoice stays open while dunning retries | Unchanged until you decide it is churn | | Cancellation at period end | No new invoice | -$50 when the period ends | The figures are a labeled hypothetical. The rule they show is general: cash arrives on the invoice date, while MRR spreads the value over the months it covers. ## Monthly or annual billing Annual billing gives the vendor cash up front and a 12-month commitment. In exchange, vendors usually discount it. Zapier's pricing page is a clear public case: its Professional plan with 750 tasks is listed at $19.99 a month billed annually and $29.99 billed monthly ([Zapier pricing](https://zapier.com/pricing), as of October 2026). **Example:** the same plan, paid for one year in each way. - Billed annually: $19.99 x 12 = $239.88 a year. - Billed monthly: $29.99 x 12 = $359.88 a year. - Difference: $359.88 - $239.88 = $120.00 a year. - Discount for paying annually: $120.00 / $359.88 = 33.3%. For the vendor, that annual customer adds $239.88 / 12 = $19.99 of MRR, not $239.88 in the month the money arrives. Reporting the full prepayment as one month's revenue inflates a growth chart by accident. The customer's side of the trade is simple. Annual billing saves a third here, but it ties the money for a year. Pick monthly while you are still testing whether a tool fits, and annual once you know it does. ## Upgrades, downgrades and proration When a customer changes plan in the middle of a period, a fair bill charges only for the time on each plan. Stripe's documentation gives the standard case. A customer upgrades from a $10 monthly plan to a $20 plan halfway through the period. The invoice credits $5 for the unused half of the old plan and charges $10 for the remaining half of the new one, so the customer pays $5 more ([Stripe, Prorations](https://docs.stripe.com/billing/subscriptions/prorations)). Two details from the same page matter in practice. Stripe prorates to the second by default, so the amount changes slightly between a preview and the actual change unless you fix the proration date. And negative prorations, the credits from a downgrade, are not refunded or paid out automatically: they reduce future invoices unless someone refunds them by hand. **Example:** a team plan priced per seat, a labeled hypothetical at $15 per seat per month on a 30-day billing period. The customer has 10 seats and adds 5 with 12 days left. - Full-month price of the new seats: 5 x $15 = $75. - Share of the period remaining: 12 / 30 = 0.4. - Prorated charge now: $75 x 0.4 = $30. - Next full invoice: 15 x $15 = $225. - MRR change: +$75, from $150 to $225. The customer pays $30 today, and MRR rises by the full $75. Mixing those two numbers up is a second reporting error to avoid. ## What subscription billing software does You can bill a handful of customers by hand. Past that, a billing system runs the schedule for you. It stores the plans, creates invoices on each renewal date, calculates proration, retries failed cards, sends receipts and reports MRR. Some also handle sales tax and the customer portal where people update their card. These systems usually charge a share of what they bill. Stripe Billing lists a fee of 0.7% of billing volume, on top of payment processing fees ([Stripe Billing pricing](https://stripe.com/billing/pricing), as of October 2026). At $50,000 of subscriptions billed in a month, that is $50,000 x 0.7% = $350 for the month, before card fees. Compare that with the hours someone would spend on invoices and failed-payment emails. For how the price itself is structured, flat, per seat, tiered or usage-based, see [SaaS pricing models](https://saascron.com/saas-pricing-models/). ## Renewal and cancellation rules Automatic renewal is convenient for both sides until a customer feels trapped by it. For consumer subscriptions, renewal and cancellation are regulated, and the rules are moving. The Federal Trade Commission's page on its Negative Option Rule lists a February 2026 revision "to conform these rules to federal court decisions". It also lists a March 2026 request for public comment on new rulemaking ([FTC, Negative Option Rule](https://www.ftc.gov/legal-library/browse/rules/negative-option-rule)). State laws add their own requirements. If you sell to consumers, have a lawyer check your renewal notices and your cancellation flow. If you sell to businesses, put the renewal date, the notice period and the price-change terms in the contract in plain words. ## Common mistakes 1. **Counting an annual prepayment as one month's revenue.** It makes a single month look twelve times bigger than it is. Why it happens: the payment report shows cash, not recurring revenue. Instead: divide annual plans by 12 for MRR, as in the table above. 2. **Promising refunds on downgrades that the system does not make.** Credits from a downgrade usually reduce the next invoice rather than return cash. Why it happens: support agents assume a credit means a refund. Instead: write down your downgrade policy and preview the invoice before confirming the change. 3. **Treating failed payments as cancellations.** A declined card is often an expired card, not a customer who wants to leave. Why it happens: no dunning process exists, so access simply stops. Instead: retry the charge on a schedule and email the customer before you cut access. 4. **Hiding the cancellation path.** A hard-to-find cancel button produces chargebacks and complaints, and can break consumer rules. Why it happens: it looks like a cheap way to cut churn. Instead: make cancellation as easy as sign-up and ask one question about why the customer is leaving. For how churn turns into customer lifetime value, see [LTV in SaaS](https://saascron.com/saas-ltv/). For how subscription revenue, churn and acquisition cost fit together, see [the SaaS business model](https://saascron.com/saas-business-model/). ## Sources - Zapier, [Pricing](https://zapier.com/pricing), checked October 2026. - Stripe, [Prorations](https://docs.stripe.com/billing/subscriptions/prorations), checked October 2026. - Stripe, [Billing pricing](https://stripe.com/billing/pricing), checked October 2026. - Federal Trade Commission, [Negative Option Rule](https://www.ftc.gov/legal-library/browse/rules/negative-option-rule), checked October 2026. ## In three sentences A SaaS subscription charges a recurring fee per billing period, renews automatically and prorates any change made in the middle of a period. An annual plan at $19.99 a month against $29.99 monthly saves the customer 33.3%, but it adds only $19.99 of MRR, never the full $239.88 in one month. Use a billing system for proration, retries and renewals, keep cash and MRR apart in your reports, and make cancellation as clear as sign-up. --- Canonical: