PKF said a separate rate of income tax in Scotland would lead to confusion and could see wealthy people declare they are not Scottish residents.
The new Scotland Act devolves new financial powers to Holyrood and was agreed by the Scottish and UK parliaments earlier this year.
It provides for a Scottish income tax which will start at 10p below the UK rate. MSPs will be able to decide how to make up the difference or whether to set a different level. The power is expected to be transferred by April 2016.
PKF said uncertainty would arise because of residency and how it is defined.
If a person has a house in Scotland, and another home elsewhere in the UK, they will be able to decide which country is their main residence.
This can be done by counting the number of days they spend in Scotland during a year.
But Neil Whyte, a tax partner with PKF, said: “As there are no border controls between England and Scotland, there is no way of verifying how many days are spent in either jurisdiction.”