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I'm sorry to hear about your situation. When you say "responsible for taxes" on the property, it's only the estate / trust that is responsible, not you personally. That is, you don't have any obligation to pay taxes on the house. It's the owner of the property that has that obligation, and if the property is in a trust, it would be the trust (through the trustee) that would be paying the taxes. Now effectively if the trust pays out everything to you, then constructively you're responsible, but only to the extent that you have an interest in the trust itself.
Now if your sister is dragging her heels and not acting to get the property sold, and you can establish that there were additional expenses incurred that would not have been incurred but for her dragging her heels (such as taxes in a new year that would be paid) then you could have a case against her for breach of her fiduciary duty. She has a duty to administer the estate quickly and not self-deal from that. Now to bring such a case you'd need a lawyer to file to remove her as executor / trustee so it's something that you would want to try to get handled without an attorney if possible. But if she's unwilling to do what she has a legal obligation to do, you would need to contact an attorney in your area that deals with probate cases. Go to www.lawyers.com or www.legalmatch.com to find an attorney in your area. You should be able to find one that will give you a free initial consultation and better advise you of your rights, any problems with your case, likelihood of success, how courts are treating cases such as yours in your area, and what you should do next.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable.
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Thank you, ***** ***** luck to you!