Commission
5.5% commission is on the higher side for North Phoenix, but it is not unreasonable. The average commission rate in the area is 5%-6%, so you are not being overcharged. However, you should try to negotiate the commission rate down, especially if you are willing to sign a longer-term contract with the agent.
If you negotiate further, it does not mean that you are being unfair to the realtors. Real estate agents are used to negotiating commission rates, and they expect to make a profit on every sale. If you are able to negotiate a lower commission rate, it simply means that the agent will make a slightly smaller profit on your sale.
FIRPTA
FIRPTA applies to all foreign sellers of US real estate, regardless of whether they have been filing US tax returns. The withholding tax rate is 15% of the gross sales price.
However, there are a few exceptions to the FIRPTA withholding requirement. One exception is if the seller has a US tax treaty with a country that has a reduced withholding tax rate. Another exception is if the seller is able to obtain a withholding certificate from the IRS.
To obtain a withholding certificate, the seller must file Form 8288-B with the IRS at least 30 days before the closing date. On Form 8288-B, the seller must estimate their net capital gain from the sale of the property and request a reduced withholding tax rate. The IRS will then review the seller's request and issue a withholding certificate, if approved.
If FIRPTA does apply to you, you should not try to play around with the number to avoid paying the withholding tax. The IRS is very strict about FIRPTA compliance, and if you are caught trying to evade the tax, you could face significant penalties.
Recommendation
I recommend that you interview several real estate agents before you choose one to sell your property. Be sure to ask each agent about their experience selling homes in North Phoenix and their commission rate. You should also ask each agent about their plan for marketing and selling your property.
Once you have chosen a real estate agent, be sure to get everything in writing. This includes the commission rate, the marketing plan, and the closing date.
You should also consult with a tax advisor to discuss your FIRPTA liability. Your tax advisor can help you determine if you are eligible for any exceptions to the FIRPTA withholding requirement and can help you file the necessary paperwork to obtain a withholding certificate, if needed.