Using unsettled funds to buy mutual funds in a margin account. Do I need to pay margin interest?

I’m trying to figure out security settling rules.

Say I have a margin account and I own 100 settled shares of ABC stock. I then sell my ABC shares and on the same day I use the unsettled funds from that sale to purchase the XYZ mutual fund.

Since ABC stock settles T+2 and the XYZ mutual fund settles T+1, it means on T+1 I’m using unsettled funds from ABC to settle XYZ, right? Will that result in a one day margin loan and thus I will be charged interest for it?

Update: I’m in US and I’m talking about the US market. Sorry didn’t realize I should make it clear first.

I talked to my broker (Schwab) and they said yes I’d be charged margin interest despite that the ‘settled fund’ number on the Balances page was including the money from a stock sale I did on the same day (which was why I had this question).