No Fee, No Interest Loan for 1 month?

[Adidas]

I have an account that gives 3% interest on my checking account (LMCU) and I thought it would be nice to top it off to 15k, let it sit until the end of the month, and then pay off the bill. Obviously this only works if my interest rate on the loan is <3% or if the interest doesn’t start accumulating until the end of the billing period.

CCs let you use your credit without interest for a month at which point you have to pay in full or you’ll owe interest. However they usually have cash advance fees. Various LOCs (HELOC, PLOC, CLOC) give you access to cash with no cash advance fee but start earning interest immediately.

Is there any product that gives both access to cash without a fee and doesn’t earn interest until the end of the month? I’m hoping for a no cash advance fee (with deferred interest) CC or a LOC with an interest grace period, etc.

Obviously I doubt such a product exists, after all the saying is “there’s no such thing as a free lunch”, but I thought I’d ask. A few ideas I’ve had that come close:

• I know some CUs (like NFCU) have no cash advance fee CCs but they usually start earning interest immediately.
• Services like Plastiq advertise themselves as a way to pay rent with a CC. They charge a 2.5% fee so with a 2% cash back CC you get pretty close to break even. I think the way they work is they basically write a check for you and send it to pay the rent. If so there could be a similar service that coverts CC- > check that you could use to write yourself a check and accomplish the goal. Obviously the fee would need to be 2% not 2.5% though.
• Just hop between 0% apr promo rates on new CCs to get a similar effect. Would prefer to avoid this for now to preserve my credit score from regular new apps, young accounts, etc.

[Revelate]

That seems like a awful lot of work for $37.50 per month and that's assuming you had nothing in the account to begin with and the cash landed the first of the month... to say nothing on what even LMCU might think (don't crap where you eat).  

Actually, case in point the 50k CSP bonus being offered currently is in excess of that, and there are a number of saving/checking account bonus offers where you could just rotate cash through to pick up at least till Chex caught up with you... but I don't worry about that personally.

That said, Unify CU has some short term loan options but they are WAY out there when it comes to CU lending products; you're going to have to look in the margins and usually there will be a fee somewhere which is going to reduce your return as you rightly point out.