With taxes, probate, guardians and other potential legal issues, estate planning is plenty complex already — and that's assuming you're married.

Gays and unmarried straight couples face special complications when it comes to transferring property at death or naming others to watch after their affairs in case of incapacity. The law accords married spouses many privileges and protections that unwed couples don't receive.

"There are something like 1,000 rights that accrue to married couples under state law," said Michael Tucker, an estate-planning attorney at law firm Polese, Pietzsch, Williams & Nolan in Phoenix.

Unmarried partners, by contrast, "are legal strangers to each other," he said.

That's why it's critical for people in nonmarried unions, whether gay or straight, to state their wishes, goals and other directives in writing.

"If you're a nontraditional couple, you better have a will or something else in writing, and you better cross all your t's and dot all your i's," said Dean Fink, a commissioner at Maricopa County (Ariz.) Probate Court. "That's the only way to give legal status to your partner."

When children are involved, estate planning for unwed couples can get more complex.

Consider the case of Shelli Guthrie and Debie Jarnagin, a same-sex Phoenix couple with four children ranging in age from 9 to 12.

Jarnagin adopted the four children by herself, because Arizona law prohibits unmarried couples from adopting. That means she needed to provide written authorization, through a legal directive called a power of attorney, allowing Guthrie to make decisions involving medical care, schooling and other issues affecting the kids.

The powers of attorney also let them make financial and health decisions for each other in case of incapacity, and they have wills for transferring assets to each other at death.

"If anything happens to one of us, everything goes to the other," Guthrie said. "If something happened to both Debie and me, the kids would be cared for by their godparents."

When singles or unwed couples die without a will, trust or other directives that name beneficiaries, their assets will pass to relatives through the probate system, following the rules of intestacy.

Wills and trusts aren't the only documents that can transfer assets to beneficiaries. Other options include pay-on-death titling for bank accounts, transfer-on-death titling for securities accounts and beneficiary deeds for real estate.

Also, IRAs, 401(k) plans, life insurance policies and annuities let you name beneficiaries. Except for wills, these various directives transfer assets outside the court-supervised probate system.

Angela Ellsworth and Tania Katan, a same-sex couple in Phoenix, have taken advantage of several of those directives, including estate-planning documents to oversee their respective business interests.

Both women have histories of cancer, and they consider it especially important to specify healthcare rights and responsibilities for each other.

"Without legal documents, we have no power of attorney in case of a medical emergency. We are concerned about our wishes being honored in our absence," said Katan, a writer and performer. "Estate planning is the closest way for us to legally state that we are a committed couple."