[logicallee]

[deleting my comment as it is not relevant.]

[cperciva]

I don't know about the USA, but in some countries you can claim a "reserve" for accrued but unpaid amounts in some circumstances. Worth talking to an accountant to see if that's a thing in your case. (Note, there's also "reserve for doubtful accounts", which is if you're not sure if you're going to end up getting paid. It sounds like that one wouldn't apply; I mention it just to be clear that I'm not talking about that sort of reserve.)

[JumpCrisscross]

There is no situation in America where you need to pay tax on a general invoice within two weeks of receiving payment.

[gamblor956]

That's not true. Self employed individuals may need to make an quarterly estimated tax payment if the payee does not withhold on the payment.

A payment recieved at the end of a quarter would be included in the ETP due 2 weeks later.