Seven phases, in order, with the failure points called out. Hold your vendor or partner to every one of them.
The software almost never kills an HCM project. The implementation does. Industry surveys keep finding that a large share of HCM implementations run late, run over budget, or go live with payroll errors. The pattern behind nearly every failure is the same: a phase got rushed or skipped. This checklist is the antidote. Work it in order.
Discovery is where your implementation team learns how you actually pay people. Document every pay rule, accrual policy, deduction, earning code, approval chain, and union or regulatory requirement. Map every integration: GL, benefits carriers, 401(k), background checks, job boards.
Failure point: letting discovery be a one-hour kickoff call. If your implementer is not asking uncomfortable questions about your weirdest pay scenarios, they are configuring a generic system you will fight for years.
Export employee demographics, pay history, accrual balances, deductions, direct deposit details, tax setups, and year-to-date totals from the old system. Clean the data before it goes into the new one. Duplicate employees, stale records, and wrong tax jurisdictions migrate just as easily as good data.
Failure point: migrating mid-year without validated year-to-date totals. Get this wrong and your W-2s will be wrong in January, and you will find out from angry employees.
This is the build: pay rules, time policies, accrual engines, org structure, security roles, workflows, and reports. Validate each configuration against the discovery document, not against memory. Test the edge cases here, on purpose: the employee who works in two states, the manager who is also hourly, the retro pay adjustment.
Failure point: sign-offs from people who never touched the system. Make the person who runs payroll approve the payroll config.
Run payroll in both systems for at least two full cycles and reconcile to the penny. Every variance gets explained: gross pay, taxes, deductions, net pay, employer liabilities. Two clean parallels is the minimum. Complex pay environments should run three.
Failure point: accepting "close enough." A $40 variance across 300 employees is not rounding. It is a misconfigured rule that will compound every cycle.
Train three audiences separately: administrators who run the system, managers who approve time and requests, and employees who use self-service. Record the sessions. Build quick-reference guides for the five tasks each group does most.
Failure point: training everyone three weeks before go-live. People forget. Train close to launch and keep office hours open for the first month.
Pick a clean cutover date, ideally the start of a pay period and a quarter. Freeze changes in the old system, take a final balance snapshot, and confirm the first live payroll preview against your last parallel run before you submit it.
Failure point: going live during open enrollment, year-end, or your busy season. Pick a quiet window. There is no prize for a December go-live.
The first 30 to 60 days after go-live need a named support contact, a daily issue log, and fast turnaround on fixes. The first off-cycle event, the first new hire, the first termination, and the first quarter-end filing are all tests the system has not faced yet.
Failure point: the handoff cliff. If your implementation team disappears at go-live and support becomes a ticket queue, small issues stack up into a crisis by the second month. Confirm the hypercare plan in writing before you sign the contract, not after.
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