IRS Interest paid to the tax payer

I am wondering how to calculate the interest I will receive on my tax return. My tax return is 3 months overdue due to COVID and I've heard the IRS is paying interest, but from the articles I've read, I'm unsure of how they calculate it.

I read that 3rd Quarter interest rate is 5%

Is this calculated per day? Is it per annum?

I'm so confused on how it's figured.

Just as an example, say I'm receiving $1500 refund.

Do I take 1500 x .05 and the $75 is my total interest paid?

Or is it per day that its overdue? so like $75 per day in interest? 

Or maybe neither one of these is right?

Can someone break this down for me?