Investors in all parts of the UK will face increased costs if Scotland votes for independence, Hargreaves Lansdown has warned.
Responding to queries from clients, the D2C platform giant said if the "yes" vote wins out financial firms will be left dealing with customers in two jurisdictions, more than likely pushing up their operating costs.
Hargreaves Lansdown's head of pensions research Tom McPhail said: "Ultimately, if UK financial institutions find themselves having to deal with customers in two different jurisdictions, that is likely to lead to a general increase in the cost of all financial products and services."
The firm also suggested Scottish savers and investors may find they are treated as they had emigrated from the UK when it comes to certain products such as NISAs.
This would mean while tax reliefs remain in play on any accrued savings held in NISAs or other products, those based in Scotland would not be allowed to save any more into them.
As well as the tax status of NISAs, questions to the firm included concerns about capital risk and the status of investment trusts with UK shares.
Polls on the outcome of the Scottish referendum vote have tightened in the past few weeks, with a 7 September YouGov poll putting the Yes campaign ahead for the first time.
Sterling tumbled against the dollar when markets opened the following day, reaching its lowest level since November 2013.
Meanwhile, spreadbetting firm IG has raised the chance of a Yes vote from 15%to 23% in the space of a week.