Delaware Tax Residency (183-day rule)

Key parameters
Threshold	183 days
Period / Window	Tax year (1 Jan – 31 Dec)
Counting	Any part of a day
Alternative	Domicile
Additional requirements	Place of abode in Delaware

This applies to anyone with somewhere to live in Delaware, whichever state they treat as their own. You are a Delaware resident if either of these applies:

• Domicile — Delaware is your permanent home, for as long as that domicile lasts.
• Abode plus days — you maintain a place of abode in Delaware and spend more than 183 days of the tax year in the state.

What sets Delaware apart is a detailed exception for people living abroad. Someone domiciled in Delaware is not treated as a resident for a period where all of these hold together:

• present in a foreign country for at least 495 full days in any consecutive 18-month period,
• present in Delaware for no more than 45 days during that 18 months,
• keeping no Delaware abode at which a spouse, children or parents are present for more than 45 days, and
• not employed by the United States government or its agencies.

The family-presence condition closes the obvious gap of leaving a household behind.

• The overseas exception counts full days, not part-days. 495 full days is a stricter measure than the ordinary day count used for the residency test itself.
• Leaving your family behind defeats it. A Delaware abode where a spouse, children or parents are present for more than 45 days puts the exception out of reach whatever your own absence.
• Government employees are excluded. Working for the United States or its agencies takes the overseas exception away entirely.
• The exception's window is 18 months, not a tax year. It runs across any consecutive 18-month period, so it does not line up with the ordinary annual count.
• Domicile lasts only as long as it lasts. Delaware treats someone domiciled there as resident for the extent of the period of that domicile, so a mid-year change splits the year.

A resident is taxed on income from all sources while a nonresident pays only on Delaware-source income, so an error usually surfaces as out-of-state earnings never reported while another state taxed the same income. The Division of Revenue charges interest from the original due date and adds penalties for filing late and for underpaying, with greater exposure where an understatement is treated as deliberate. Professional tax advice is strongly recommended in situations like this.

A rented house and a working year

You are domiciled in Maryland, rent a house in Wilmington all year, and are in Delaware most working days. Both limbs hold, so you are a Delaware resident.

A posting abroad that qualifies

You are Delaware-domiciled and take a two-year role in Singapore, spending 500 full days abroad in an 18-month stretch and returning for about 30 days. Your family comes with you, so the overseas exception applies for that period.

A posting abroad undone by the family home

You take the same role but your spouse and children stay in the Delaware house all year. Their presence there for more than 45 days defeats the exception, so residency continues.

• Delaware Code — Title 30, Section 1103, resident individual defined
• Delaware Division of Revenue — Personal income tax FAQs