Mr Joyce said he was reserving the right to proceed with Datacom earlier if required.
Deloitte said Novopay could be fixed if greater effort was made by Australian provider Talent2 and the ministry. "We do not believe that long term stability can be delivered by the current processes and resources. It would require materially elevated and sustained effort and capability by both the ministry and Talent2.
"The work required to achieve long term stability is therefore feasible but difficult," Deloitte found.
The review found Novopay was not properly processing annual leave and holiday pay, end of school-year payments, bulk leave and timesheet bookings, terminations, service accumulation and sick leave.
Mr Joyce said progress was being made on stabilising Novopay by boosting the number of staff working on processing pay at both the Education Ministry and Talent2.
"In the last three fortnightly pay periods, the percentage of complaints and notifications received dropped from 2.2 per cent to 1.9 per cent to 1 per cent."
Deloitte recommended mistakes would have to be reduced to consistently below 1 per cent. It said there would have to be no very serious defects, and serious defects would need to be fewer than 10.
The Post Primary Teachers Association were pleased with the $6 million payout, but president Angela Roberts said legal action seeking compensation for "hurt and humiliation" would continue.
Teacher payout
The $6m one-off payout to schools includes $105 paid to each full-time teaching equivalent, plus $500 per school, meaning:
* A small school with five teachers would receive $1025.
* large school with 120 full-time teachers would receive $13,100.