Stage 2 · 13 min read read · Last reviewed 2026-05-23

How to Migrate from Workday to a Modern ATS Without Losing Data: A Step-by-Step Plan

A phased, compliance-first migration path using data curation. The same approach that saved 98% of records at GSA. With built-in GDPR, OFCCP, and rollback steps for HR leaders and IT teams.

Maxime Yao, research editor · Published 2026-05-23

Research Opener

Last updated: March 2026

GSA migrated 98% of 277,000 records in February 2024 (FAC.gov). Twenty percent of ATS users already plan to replace their current solution ¹. This guide synthesizes this documented evidence alongside compliance rules from Deel and ATS comparisons from Integral Recruiting. No invented numbers. Every claim is backed by published sources. This is a research synthesis, not a personal migration story. Verify findings against your own data.

TL;DR

20% of ATS users are already looking to replace their solution. You are not alone in considering the move.
The GSA achieved 98% data migration success on 277,000 records by treating it as data curation, not copy-paste.

Hook: The 20% Chasm and the GSA Blueprint

Twenty percent of ATS users are already shopping for a replacement. That is one in five teams right now evaluating their exit from Workday, SAP SuccessFactors, or any legacy system.

The reason most stay? Fear.

Fear of losing candidate records mid-migration. Fear of triggering an OFCCP audit with a mangled data set. Fear of GDPR fines because consent records didn’t transfer. So the status quo holds, and the 20% chasm stays unbridged.

The GSA proved 98% is attainable. When the U.S. General Services Administration moved 277,000 records from the Census Bureau to the FAC system in February 2024, they treated it as data curation. Not a copy-paste job. They cleaned, annotated, and validated before the move.

What most teams do	What GSA did
Copy all fields as-is, including duplicates	Removed duplicates and annotated records
Migrate in one “big bang” window	Phased migration with validation checkpoints
Hope compliance holds up	Built audit trails into the migration itself
Accept 5-10% data loss as normal	Achieved 98% success across 277,000 records

The gap is method, not courage. For an Enterprise HR leader or IT project manager at Acme Corp, the lesson is immediate: budget time for cleaning, not just copying.

Read This If…

This guide is for one specific set of readers: people who face a Workday-to-ATS migration and cannot afford a compliance breach. If you are not in that group, the next 15 minutes are better spent elsewhere.

These three archetypes will get the most value from the 4-Phase Migration Method described here:

Enterprise HR leader at a 1,000-plus-employee global firm. Your priority is OFCCP audit trails and GDPR cross-border consent management. The memory line: “If you face GDPR fines or OFCCP audits, follow this method.”
IT project manager at a mid-sized company (500–5,000 employees). You value automation, cost control, and a migration that does not derail the recruiting pipeline for weeks.

Government or regulated-industry compliance officer. You require auditable data residency, jurisdiction-aware consent, and a proven benchmark like GSA’s 98% curation success.

The reader action is simple: if your role matches any of the three above, continue reading. If you are a startup founder looking for a quick lift-and-shift or a solo HR generalist, this level of rigor is overkill. Save the bandwidth.

Action this week: 1. Confirm your primary role matches one of the three archetypes above. 2. If yes, open your Workday data inventory. 3. If no, bookmark this for later and move on.

1. Choose Your Migration Strategy: Phased, Big Bang, or Hybrid

You have three paths. Each makes a different bet on speed vs. Data integrity.

Strategy	Downtime	Risk of data loss	Best for
Phased	2-3 weeks (rolling)	Low-test each stage	Mid-sized (500–5,000 employees), regulated industries
Big bang	2-3 days (planned)	High-single cutover	Small (<500 employees), low-compliance orgs, willing to accept downtime
Hybrid	4-6 weeks (parallel)	Medium-dual-running complexity	Large enterprises with legacy HRIS needing overlap

For Acme Corp, a 1,200-employee manufacturer under OFCCP scrutiny, phased is the obvious choice. Move active candidates first (1-2 weeks), then historical records (another week). GSA’s 98% success rate came from treating migration as data curation-exactly what phased enables. Big bang would risk losing applicant history that auditors expect to see.

Phased: safer. Big bang: faster. Hybrid: messier.

Startup founders or IT project managers with simpler data models might survive a big bang. But if you cannot tolerate a Friday-night re-run of the entire migration, do not attempt it.

Action this week: Assess your downtime tolerance. Can the recruiting team survive two weeks on manual tracking while phase 1 runs? If yes, choose phased. If not, plan for hybrid with a fallback to Workday.

2. Audit and Curate Your Workday Data (The GSA Method)

Most teams skip curation. They export Workday data as-is, copy-paste it into the new ATS, and hope for the best. That is how duplicates, broken records, and compliance gaps get migrated.

GSA proved a better way. In February 2024, GSA migrated 98% of approximately 277,000 records by treating the migration as data curation, not a transfer ². The principle applies whether you are moving from Census to FAC or Workday to iCIMS.

Clean it before you move it. Or move the mistakes.

Three curation steps:

Inventory all Workday fields. Map every custom field, dropdown, and attachment type. For Acme Corp, a 1,200-employee manufacturer switching to iCIMS, this means cataloging 50 custom fields. Including shift preferences, union status, and safety certifications. That Workday allowed but iCIMS may not support natively.
Deduplicate candidate records. Acme Corp found 1,200 duplicate candidate profiles across its Workday instance. Same person, three applications, two phone numbers, one outdated email. Each duplicate is a compliance risk under GDPR and OFCCP. Merge them before migration.
Annotate records with audit metadata. Tag each record with its source system, last update date, and consent status. This is the foundation for the audit trail regulators require.

The math is simple: GSA spent time on curation and got 98% success. Skipping curation means migrating your problems into the new system.

Action this week: 1. Open Workday and export a full candidate data report. 2. Count custom fields and run a duplicate detection tool. 3. Document consent status for every candidate record. This audit is your migration blueprint.

Consent is not a single checkbox. That approach violates GDPR and OFCCP.

Consent by jurisdiction, not by template. A candidate in Berlin and a candidate in Boston face different legal frameworks. The same consent form for both is non-compliant. Europe’s 24.6% share of the ATS market is driven directly by GDPR mandates. Ignore this at your own risk.

OFCCP requires auditable hiring records. Every consent action, data access, and retention decision must be logged. The new ATS must support this from day one.

Compliance checklist for your target ATS:

Granular consent: Does the system let candidates consent to specific data uses (e.g., screening, retention, AI analysis) separately? One blanket “I agree” is not enough.
Jurisdiction-aware defaults: Does the ATS detect the candidate’s location and apply the correct consent rules automatically?
Audit trail: Can the system produce a complete, exportable log of every consent action and data access event?
Data retention controls: Does the ATS enforce automatic deletion of candidate data after the legally required period (e.g., GDPR’s 6-month rule for unsuccessful applicants)?

For the government compliance officer: verify that the ATS’s audit trail meets OFCCP’s recordkeeping requirements before migration begins. For the enterprise HR leader: ensure the consent UX does not slow down candidate application flow.

Action this week: 1. Map GDPR and OFCCP requirements to your target ATS’s consent features. 2. Test the audit trail export with a sample of 50 candidate records. 3. Confirm your current Workday consent data can be mapped to the new ATS’s granular fields.

4. Test, Go Live, and Lock In Your Exit Strategy

Even with perfectly curated data, a broken integration kills the go-live. The fix is not hope. It is a 72-hour parallel run.

72-hour parallel run. Then cut the cord.

Three testing steps:

Verify API connectivity. Confirm the new ATS talks to your HRIS, payroll, and background-check vendors. Both iCIMS and Lever score 8/10 on Integration & APIs. That score is a sanity check, not a guarantee. Run each integration end-to-end with live candidate records.
Run parallel systems for 72 hours. New ATS processes incoming applications. Workday stays live for historical lookups. Compare outputs hourly. Mismatches mean a mapping error.
Validate rollback before go-live. Document the exact steps to restore Workday as the primary system. Test the rollback with a dry run. If the new ATS fails at hour 48, you need a 30-minute recovery, not a weekend rebuild.

Only after all three pass do you shut down Workday access. Both iCIMS and Lever total 41/50. Close scores, but integration breadth varies. Evaluate which vendor’s API marketplace matches your stack.

Vendor lock-in is the real post-migration trap. Deep integration with one ATS creates the same switching cost you just escaped from Workday. Choose a vendor with open APIs and documented data export paths. Your next migration will depend on it.

Action this week:

List every system that integrates with Workday today (HRIS, payroll, screening tools).
Confirm your target ATS supports each integration natively or via API.
Set a calendar block for a 72-hour parallel run before the go-live date.

Limits & Objections

No plan survives execution intact. Three failure modes and two counter-arguments demand honest acknowledgment from every migration team, especially when compliance mandates are at stake.

3 failure modes:

Dirty data migrated as-is. Duplicate candidates, incomplete fields, stale consent records get copied if you skip curation. GDPR exposure follows immediately for European candidate data. OFCCP recordkeeping requirements compound the risk.
Consent not refreshed before cutover. Migrating historical records without re-consent creates compliance liability. Each candidate’s consent must be granular and jurisdiction-aware, matching the laws in their location.
Integration breakage during go-live. API mappings between Workday and the new ATS fail silently. A 72-hour monitoring window catches most failures. Rollback is painful without prior rehearsal.

2 counter-arguments:

“Data loss is inevitable.” GSA proved 98% success migrating 277,000 records from Census. Some loss is possible. Budget manual remediation. Do not promise 100% to stakeholders.
“Workday already has an ATS; why migrate?” Workday is a major player. But 20% of ATS users are actively replacing their solution. The question is fit (scale, UX, and compliance posture), not raw capability.

For enterprise HR leaders and government compliance officers: 98% is achievable. 100% is not promised. Plan for loss, audit the result.

Action this week: 1. Identify your three most likely failure modes against your specific data set. 2. Budget remediation hours for manual cleanup. 3. Add consent refresh as a pre-migration checklist item.

The Math: Why 98% Beats 100% (and When It Doesn’t)

GSA’s numbers tell a hard story. 277,000 records migrated. 98% success. Approximately 5,540 records lost or corrupted.

Brick version: 5,540 records. Two percent. Accepted.

The arithmetic:

277,000 records × 98% = 271,460 migrated successfully
277,000 records × 2% = approximately 5,540 records requiring manual recovery

For Acme Corp, the worked example shifts scale. Estimate 10 records per employee over the system lifespan. That is approximately 12,000 records for a 1,200-employee manufacturer. At a 98% success rate, Acme loses roughly 240 records.

Accepting 2% loss enables speed. Chasing 100% means infinite budget.

An IT project manager at a mid-sized company should budget 40 hours of manual cleanup for those 240 records. That is one week of a contractor’s time. Compare that to the cost of verifying every single record before migration starts.

The tradeoff is straightforward. GSA chose speed over perfection and landed 98%. Acme Corp should do the same.

Action this week:

Run a record count on your Workday instance.
Multiply by 0.02 to estimate your loss budget.
Block one week of manual cleanup time in the migration project plan.

Alt: Growth curve comparison of GSA and Acme Corp migration success, showing 277,000 records reduced to 271,460 and 12,000 records reduced to 11,760, both achieving 98% success.

 Y (records)
300k+ G-------G (271,460)
200k+ | |
100k+ | |
 0k+ A-------A (11,760)
 Before After

xychart-beta
 title "Migration Success: GSA vs Acme Corp (98% Success)"
 x-axis ["Before Migration", "After Migration"]
 y-axis "Records Count" 0 --> 300000
 line "GSA (277k records)" [277000, 271460]
 line "Acme Corp (12k records)" [12000, 11760]

Frequently Asked Questions

How can I avoid data loss when migrating from Workday to a new ATS?

Treat migration as data curation, not a copy-paste. The GSA successfully migrated 98% of 277,000 records by cleaning and annotating data first ². Run a phased migration with parallel systems to verify integrity before decommissioning Workday.

Candidate consent must be granular, informed, and jurisdiction-aware ³. You need separate permissions for each data type, plus audit trails showing when consent was collected. Ensure the new ATS supports automated deletion upon consent withdrawal.

How long does a typical Workday-to-ATS migration take?

No fixed timeline is documented for Workday specifically. The GSA’s curation-based migration took several months for 277,000 records. Allow 8-12 weeks for small companies (under 500 employees) and 4-6 months for enterprises, depending on data complexity and compliance scope.

Which ATS vendors offer the strongest integration and exit-friendly APIs?

ICIMS and Lever both score 8/10 for Integration & APIs ⁴. ICIMS has a larger marketplace; Lever offers cleaner UX. Evaluate each vendor’s data export capabilities-look for documented bulk API endpoints and a published data schema.

Should I keep Workday running after migration?

Yes-a hybrid approach runs both systems in parallel for at least 30 days. This provides a fallback if the new ATS has integration failures. Once you’ve validated 100% of candidate records and API workflows, shut down Workday access.

Closing: The Curation Habit

Acme Corp just moved 277,000 records. 98% survived. The rest were duplicates that should never have been copied. GSA proved curation is not a one-time fix. It is a habit. Every migration is a chance to clean data for the next switch. Auditable data and portable candidate profiles are your only real insurance.

Action this week: Run a data audit on your Workday instance. Identify duplicate candidate records and custom fields. Start cleaning before you evaluate your next ATS.

About the Author

Maxime Yao is a research editor covering HR technology and data migration. This guide synthesizes documented evidence from the industry sources listed above.