Maximum refund guarantee looks like a PITA to actually access. Not clear to me whether you can use a workaround to still file with TurboTax and still qualify. Could be worth a try, but it's a lot of work for $50. Here's the legal language:
To qualify, the larger refund or smaller tax due cannot be attributed to variations in data you provided for tax preparation or for positions taken by you or your preparer that are contrary to the law. If you received a larger refund amount or must pay a smaller tax due using another tax preparation method other than TurboTax, you must notify Intuit within sixty (60) days of the date you filed your tax return by submitting a claim with the following documents (i) Maximum Refund Guarantee Claim Request Summary, (ii) copy of your TurboTax store sales receipt or shipment packing slip, (iii) copy of your proof of payment for another tax preparation method (if applicable), and (iv) copy of your TurboTax data file, (v) copy of the printed return from TurboTax and the other tax preparation method, and (vi) letter stating your refund or tax due amount using TurboTax and your refund or tax due amount using another tax preparation method. Send it to Intuit Inc., ATTN: Maximum Refund, 2800 E Commerce Center Place, Tucson, AZ [social security number removed], US. Please use a traceable mailing method and maintain copies of submitted items for your records. Claims of non-payment will require photocopy substantiation of all required items. Please allow up to 6 weeks for processing and delivery. If after 8 weeks you have not received your check, contact us at https://ttlc.intuit.com/community/using-turbotax/help/what-is-the-turb[product key removed]r/00/2563....
