I have 3 years of taxes to file. Where do I start? Is it best to consult a tax professional?

It is usually in your best interest to use a local tax professional when you have multiple years of tax returns to file.

It depends on how complex your returns are. just a w-2 should not require using a tax pro. any refund for 2019 is lost due to late filing but if you owe the tax authorities have an unlimited amount of time to pursue collection. you would need to use Turbotax desktop software - full pc or Mac for each year. In addition, for 2023 your computer must have a 64-bit operating system. If you have carryovers then it may be wise to use a pro.

to me a simple return would be w-2s and some dividends or interest income and not someone's dependent