Make sure to know the difference between Pay and File.

The 940 form is Year End reconciliation of wages paid for purposes of Federal Unemployment Tax. You pay that tax at the point you owe $500, if not earlier, and at least at year end. The Form is submitted after the end of the calendar year.

The 941/944 is 5 tax items (income tax withholding, employer and employee social security, employer and employee medicare) and this is paid per your IRS notice as either by the 15th of the month following paycheck dates, by the 3rd banking date following the paycheck dates, or by the next banking date following the paycheck dates, per the Notice you get as seen here:

https://www.irs.gov/taxtopics/tc757

You can hold the funds until it reaches $2,500 for the quarter, and you must pay by the end of the quarter, even if it hasn't reached $2,500.

The IRS tells you if you can be a 944 filer, which is End of Year reconciliation, only. Otherwise, you submit 941 quarterly, including the fourth quarter. You never use both 941 and 944.

I just spent time yesterday with someone whose CPA does "one payroll at year end after the fact for all distributions taken through the year, weekly" and explained this is not going to sit well if the IRS ever notices. They called me because they got a notice from the IRS and didn't understand it, regarding their 941 payment schedule is now changed to Semi-weekly (3 banking dates) and the lookback quarters listed shows Oct 2017 $0, Dec 2017 all the money, March 2018 $0 and June 2018 $0.