Project Context
You’re the program manager for ShopHub, a global e-commerce marketplace (~38M monthly active buyers, 410K active sellers) processing $6.2B GMV/month. ShopHub’s revenue is driven by seller subscriptions (Basic/Pro/Enterprise) and value-added services (ads, fulfillment). Billing is handled by a 10-year-old monolith (“BillMon”) that generates invoices, charges cards/ACH, applies taxes/VAT, and posts revenue events into the finance data warehouse.
A new microservice-based billing platform (“BillNext”) has been built by a platform team to support multi-entity invoicing, market-specific tax rules, and real-time proration. Leadership has mandated a migration because BillMon cannot support upcoming regulatory requirements and is a top contributor to incident load (average 3 Sev-2 incidents/month). The business stakes are high: billing errors directly impact revenue recognition, seller trust, and compliance.
You must produce a detailed project plan (as if in Microsoft Project or Smartsheet) to migrate 100% of sellers from BillMon to BillNext with zero downtime, while continuing to ship a separate Q2 growth initiative.
Team & Operating Model
You will lead a cross-functional program spanning 5 teams:
| Team | Size | Responsibilities | Notes |
|---|
| Billing Platform Eng (BillNext) | 7 engineers | BillNext services, APIs, eventing | Owns new system; already at 70% capacity |
| Legacy Billing Eng (BillMon) | 4 engineers | BillMon changes, data exports, incident response | Also on-call for current billing |
| Data Platform | 5 engineers | ETL, warehouse schemas, revenue event pipelines | Currently migrating to a new lakehouse |
| Finance Systems (RevRec) | 3 analysts + 1 eng | Revenue recognition rules, audit evidence | Must sign off on parity |
| SRE/Infra | 2 SREs | Reliability, monitoring, runbooks, incident response | No additional headcount approved |
You have one designer for seller-facing invoice UX changes (shared across two programs) and one QA lead who supports multiple releases.
Stakeholder Landscape (Competing Priorities)
- CFO / Finance Controller: Needs audit-ready evidence that revenue recognition is unchanged. Will block launch without reconciliation and controls.
- VP of Seller Growth: Has a committed launch to roll out “Annual Plans” by end of Q2, which depends on billing changes. Wants BillNext features ASAP.
- Director of Engineering (Billing): Wants to reduce incident load and retire BillMon, but is concerned about burnout and on-call load.
- Head of Compliance (EU): Requires VAT invoice formatting updates by a fixed deadline; prefers conservative rollout.
- Customer Support Ops Lead: Wants tooling and macros ready; worried about ticket spikes during migration.
Constraints
- Hard deadline: By June 30, ShopHub must comply with updated EU VAT invoice requirements for 8 EU markets (Germany, France, Italy, Spain, Netherlands, Belgium, Austria, Ireland). Non-compliance risks fines and forced invoice re-issuance.
- Zero downtime: No planned downtime windows are allowed; billing runs daily and invoices are generated continuously.
- Data parity: Invoice totals, taxes, proration, discounts, and refunds must match within ±0.1% at an aggregate level and exact match for a defined set of high-risk seller cohorts.
- Resource limits: No new hires/contractors. SRE can only dedicate 10 hrs/week until launch week.
- Dependencies:
- Payment processor tokenization changes must be completed by a separate Payments team by Week 4.
- Data Platform is mid-migration; they can offer only one engineer for BillNext ETL work for the first 6 weeks.
- Operational risk: BillMon is fragile; any large change increases incident likelihood.
What You Need to Produce (Deliverables)
- A detailed project plan (work breakdown structure) suitable for Smartsheet/MS Project, including:
- Workstreams, tasks, owners, durations, dependencies, and critical path
- Explicit milestones and entry/exit criteria per phase
- A launch strategy that supports zero downtime (e.g., dual-write, shadow reads, phased cutover), including a rollback plan and decision gates.
- A trade-off proposal for handling the competing “Annual Plans” initiative vs. migration scope, with a clear recommendation and rationale.
- A risk register with top risks, triggers, mitigations, and contingency actions.
- A stakeholder alignment plan: cadence, artifacts (weekly exec readout, RAID log), and how you’ll secure sign-offs (Finance, Compliance, SRE).
Complications (Assume These Happen Mid-Project)
- Week 3: The Staff Engineer who owns BillNext’s proration engine announces they are leaving in 4 weeks. Knowledge transfer is incomplete.
- Week 5: The Payments team slips tokenization changes by 2 weeks, impacting end-to-end charge flows.
- Week 7: A Sev-1 incident in BillMon consumes the Legacy Billing team for 4 days and increases leadership scrutiny.
Your answer should reflect how you would build and maintain a professional plan in Smartsheet/MS Project: how you structure it, how you manage dependencies, how you surface critical path, and how you keep stakeholders aligned when reality diverges from the plan.
