A company's year comes down to a short list of dates, and most of them won't apply to your company. Here's the full list for a calendar-year company owned from abroad, with who each date applies to, so you can cross out the rest. The compliance calendar on every plan shows the ones that apply to you.
An owner with US-taxable income may also have to make estimated tax payments of their own during the year.
For most foreign-owned single-member LLCs
Two dates: Wyoming's annual report on the first day of the month you formed in, and Form 5472 with the pro forma 1120 by 15 April. Add 31 January if you paid US contractors by bank transfer or cheque. The rest of the list is for other kinds of company, or for owners with US-taxable income, which a company run from abroad with no US presence doesn't usually create.
Extensions
Form 7004, filed by the original due date, gives a business six more months to file: to 15 September for Form 1065, and to 15 October for Form 1120 or the pro forma 1120 with Form 5472. It extends the time to file, not the time to pay, so any tax owed is still due on the original date. Plenty of LLCs whose books aren't ready by spring file the extension and send the return in the autumn.
Fiscal years
Almost every small company uses the calendar year, and the dates above assume it. A corporation can choose a different year end, and its Form 1120 is then due on the 15th day of the fourth month after it. A foreign-owned single-member LLC uses its owner's tax year for US filings or, if the owner has none, the calendar year.