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Trading with Settled / Unsettled Funds (T+3)
The issues of trading with unsettled funds are usually restricted to cash accounts.  With margin, I've never personally heard of a rule that will catch you in this scenario.  You won't be able to withdraw funds that are tied up in unsettled positions until the positions settle.  You should be able to trade those funds.  I've never heard of a broker charging margin interest on unsettled funds, but that doesn't mean there isn't a broker somewhere that does. Brokers are allowed to impose their own restrictions, however, since margin is basically offering you a line of credit.  You should check to see if your broker has more restrictive rules. I'd guess that you may have heard about restrictions that apply to cash accounts and think they may also apply to margin accounts.  If that's the case and you want to learn more about the rules generally, try searching for these terms: You should be able to find a lot of clear resources on those terms.  Here's one that's current and provides examples: https://www.fidelity.com/learning-center/trading-investing/trading/avoiding-cash-trading-violations On a margin account you avoid these issue because the margin (essentially a loan from your broker) provides a cushion / additional funds that avoid the issues.  It is possible that if you over-extend yourself that you'll get a "margin call," but that seems to be different than what you're asking and maybe worth a new question if you want to know about that.