phase in(redirected from phases in)
To introduce or implement (something) gradually, especially in distinct phases or stages. We've been phasing in a new company-wide policy to help deal with cyber security threats. The program was phased in over a period of seven years, with the final implementation going live today.
Introduce one stage at a time. For example, New technology must be phased in or the office will be overwhelmed. The antonym is phase out, meaning "to bring or come to an end, one stage at a time," as in The department is phasing out all the older computers. [Mid-1900s]
To introduce something or someone gradually or in stages: The government is now phasing in a new immigration policy. We should phase the new regulations in slowly so that businesses can get used to them.