Federal returns are to be postmarked or sent electronically by tomorrow night at midnight. The tax deadline falls on April 17 this year because the April 15 was a Sunday and today is a holiday in Washington, D.C. The deadline for state income tax returns is April 20.

The IRS sent out a reminder today saying people who file paper returns can avoid delays in processing if they send in error-free returns. It said some of the most common mistakes are failing to sign, putting in all of the required Social Security numbers, and attaching all required schedules.

People also should double-check their numbers.

Residents who won't make the filing deadline, can file for an extension that sets Oct. 15 as the new due date. People filing the extension request, Form 4868, need to include a check for their estimated tax payment if they owe the government money.

The U.S. Postal Service said it will have late pick ups tomorrow night. People using this service should deposit their mail in specially marked collection boxes at the following locations:

Oahu

Airport Main Post Office

Downtown Post Office

Ewa Beach Post Office

Haleiwa Post Office

Kailua Post Office

Kaneohe Post Office

Kapalama Post Office

Laie Post Office

Makiki Post Office

Mililani Post Office

Waialae-Kahala Post Office

Waianae Post Office

Waikiki Post Office

Waipahu Post Office

Maui

Kahului Post Office

Kihei Post Office

Lahaina (Main) Post Office

Makawao Post Office

Wailuku Post Office

Hawaii

Hilo (Airport) Post Office

Kailua-Kona Post Office

Kamuela Post Office

Kauai

Lihue Post Office

Molokai

Kaunakakai Post Office

Lanai