The U.S. Supreme Court is set to decide whether same-sex marriage must be allowed in all states, but even this momentous decision will not solve all financial issues that same-sex couples might face, say experts.

The top court has heard arguments on cases brought by 15 same-sex couples in four states and is expected to issue a decision late next month. If the court rules in favor of the plaintiffs, all states will have to recognize same-sex marriages. Currently, 36 states do so.

But rules applying to married couples, whether same sex or opposite sex, vary from state to state and that hodge podge will continue even if the Supreme Court recognizes same-sex marriage nationally, says Matthew T. McClintock, vice president of education for WealthCounsel, an advisory firm for lawyers.

To gain control of life decisions and estate planning, same-sex couples should put their wishes in writing now without waiting for the Supreme Court decision, say McClintock and Katie C. Williams, vice president of Diversified Trust Company, a wealth management firm in the southeast United States.

The default rules of each state apply if a couple does not legally document their wishes, McClintock says. For instance, when someone dies without a will, states designate different percentages his or her spouse and children will inherit, but these percentages may not match what a person wishes to leave heirs.

Revocable trusts can be useful in distributing assets. Revocable trusts are not subject to probate in some states, says Williams, so assets can pass directly to a beneficiary and allow heirs to avoid the expense and time involved in the probate process. A revocable trust can be changed as a couple’s circumstances change.

McClintock also noted same-sex couples should consider how they want the courts to treat their children. “The same-sex couple with children has to be treated as a blended family,” McClintock says. “What happens to the rights of the biological parent who is not part of the couple? A same-sex partner who is not a biological parent should consider adopting the child to establish his or her rights.”

Cash, investment accounts and real estate assets should be put into joint ownership so they can pass automatically to the surviving joint owner, Williams says.

“All of these suggestions should be discussed with knowledgeable lawyers or financial planners because there are many issues to consider in making these choices,” she adds.

What it comes down to, according to McClintock, is that “the default rules in most states are inadequate. If same-sex couples are not proactively planning, the courts [in each state] will make the decisions.”