You need to get an employment letter to show at the interview. Take one copy for yourself and one copy for each of your dependents. Some consulates don't accept I-134 for supporting your dependents.

Employment letter should

• Reaffirm that the job offered in the approved preference petition is still open and available to you as soon as you immigrate.
• Confirm the current salary, not the labor certificate salary.
• Give a description of the job offered to the alien and explanation of skills which qualify the alien for the position.
• Indicate start date, job title

This letter must be notarized in US with a notary public. Sample employment letter.

Note: No one is being asked for sailing permit for last several years since employment based consular processing has been going on. Hence, it is up to you whether you would like to get it or not.

If you are either a resident or a non-resident alien departing the United States, you will usually have to show your compliance with the U.S. income tax laws. You do this by obtaining a tax clearance document, commonly called a "Sailing Permit" or "Departure Permit," from the IRS. (For USCIS purpose any one who does not have green card are non-resident alien, but for IRS purpose even non green card holders who have stayed in US for 182 days are considered resident alien. For information about resident or non-resident alien for IRS purpose, refer to Publication 519, U.S. Tax Guide for Aliens).

It is legally possible for the government to prevent someone from leaving if they don't have sailing permit. This permit is rarely asked for at the consular post, but it advised that every immigrant applicant should carry this before going for the interview.

If you do not have taxable income, or you are a resident alien who is leaving only temporarily, use fillable (type in) Form 2063 to apply for a sailing permit. If you are a resident alien leaving the United States with no definite plans to return for the year, you will have to complete Form 1040-C, U.S. Departing Alien Income Tax Return, in order to get a sailing permit. Nonresident aliens who have any taxable income will also have to complete Form 1040-C to receive a sailing permit. You must pay all tax shown as due on the Form 1040-C unless you furnish a bond or an employer letter guaranteeing payment, or the IRS is satisfied that your leaving will not jeopardize collection of the tax. Any tax you pay counts as a payment on your final return that you file after the end of your tax year.

Apply for the sailing permit no earlier than 30 days before you plan to leave. You should apply at least two weeks in advance of your departure. To get your sailing permit, visit your nearest walk-in IRS office. If you are married to an alien who is leaving the country with you, both of you must go to the IRS office.

You must bring with you all the following records and information for the current year, that apply:

• A valid passport and your alien registration card or visa,
• Copies of the last two years' income tax returns with proof of payment of any balance due,
• A statement from each current employer showing the wages paid and tax withheld from January 1 of the current year to the date of departure. For this statement you can use a payroll deduction slip for your last paycheck if it shows this information.
• If you are self-employed, a profit and loss statement for the current year to the date of departure.
• Documents showing any gain or loss from the sale of personal property, including capital assets and merchandise.
• Proof of tax payments for the past year and this year.
• Documents concerning scholarships or fellowships.
• Documents indicating that you qualify for special tax treaty benefits.
• Substantiation of deductions for business expenses and itemized deductions.
• Documentation for dependents claimed.
• Airline return tickets.

If you have these documents and pay any tax due you should receive your sailing permit immediately.