If you are asking about an IRS installment agreement, they are pretty understanding if this is your first late payment, and do offer some options for you, depending on what you can do.
I suggest IRS2Go, which will allow you to pay online directly, without the lengthy online enrollment of EFTPS. IRS2Go will process payments from a credit card, debit card or your checking account.
IRS offers a few other options on that page, including EFTPS (signup will not be effective today) and others.
https://www.irs.gov/payments is the link to set up and pay.
If you can't make this online payment work, call IRS. 1-***-***-**** is their general number. You can simply notify them of the reason for the late payment. They will likely just note your account, and will be fine with waiting until you are back home (if you have a good payment history).
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