Costs & Contracts
Part of Marketing technology costs and contracts
Calculating stack cost beyond subscription fees
Build a marketing stack cost model that includes setup, variable charges, operating work and exit alongside subscriptions.
Calculate stack cost over one decision period. Add supplier payments and the work needed to set up, operate and leave each tool. Show cash spend and internal effort separately, so neither is hidden in a subscription total.
Set the period and cost basis
Use the proposed commitment term or another period that fits the decision. Put supplier figures on the same currency and tax basis; for an Australian budget, state whether figures include GST.
Record an exchange-rate assumption for invoices in another currency. Convert monthly charges and one-off quotes to the chosen period before adding them.
Make one row per cost, owner and payment date. Label amounts as confirmed, quoted or estimated.
For a shared system, record who pays and whether the marketing proposal creates an additional charge. Count an existing company-wide licence only when its cost is relevant to the decision, and show it separately from new cash spend.
Cost group / Items to investigate
- Supplier commitment
- Licence, minimum seats or volume, required onboarding and paid support
- Variable charges
- Billable contacts, sends, credits, message segments or other relevant usage
- Delivery
- Migration, integration, agency work and training
- Operation
- Administration, data upkeep and recurring specialist work
- Exit
- Export, transition support and any period of running two systems
Include a category only when it applies. Mailchimp’s current paid monthly marketing plans may add charges when contact or send limits are exceeded.
Stack Cost Components: Supplier Commitment vs. Internal Effort
- Supplier Commitment (Cash)
- Licence fees, minimum seats, onboarding, paid support
- Variable Charges (Cash)
- Billable contacts, sends, credits, message segments (e.g., Mailchimp, Twilio)
- Delivery (External Work)
- Migration, integration, agency work, training
- Operation (Internal Effort)
- Administration, data upkeep, specialist work (hours × planning rate)
- Exit (Transition Costs)
- Export, transition support, dual-system run period
Calculate ordinary and busy cases
Write the billing rule beside each variable-charge forecast. Mailchimp says the peak contact total during a billing period affects the monthly bill. An average audience or message count can therefore conceal a costly month.
Use this cash formula: period cost = committed supplier charges + forecast variable charges + external delivery and operating charges. If the organisation wants a resource view, add internal hours × an agreed planning rate on a separate line. That rate is a budgeting assumption, not a supplier fee or necessarily another cash payment.
Recalculate for a plausible campaign peak and a quieter period. Keep quantities, rates, thresholds and assumptions visible. Check when a lower tier or reduced commitment can affect the bill; lower use alone may not reduce it.
Building a Stack Cost Model: Key Steps
- Define the decision period and cost basisUse commitment term; apply GST where relevant; convert foreign currency using assumed exchange rate
- Identify cost groups and their driversInclude supplier commitment, variable charges, delivery, operation, exit; label as confirmed, quoted, or estimated
- Forecast ordinary and busy-case scenariosApply billing rules (e.g., peak contact count); recalculate for campaign peaks and quiet periods
- Reconcile forecast with actualsCompare model to invoices and usage records; update assumptions when changes occur
Key Cost Drivers in Australian Marketing Stacks
- GST Inclusion
- State whether figures include GST (mandatory in Australia)
- Mailchimp Overages
- Additional charges apply if contact or send limits exceeded (per billing period)
- Twilio Messaging Costs
- Charged per message segment; varies by destination country
- HubSpot Contact Billing
- Based on active marketing contacts; includes seat-based tiers
Reconcile the forecast
Compare invoices and usage records with the model, then explain material differences by cost group. HubSpot documents account views for subscriptions, seats, marketing contacts and billing documents. Twilio documents invoice and usage views.
Update the model when volume, integrations or an agreement changes. Its output should show the cash commitment, internal effort and the assumptions that could move either figure.
