Just by looking to the domain name you should name that it dosen't look professional at all , they will probably use the informations you provide for Mtgox to get your coins back for them selfs and not to contact you .
website is having like ~100 visitor per days (and what kind of le git website have that) which could be even fake using traffic exchange platforms . I'd recommend you to stay out of it
Still , you can see that someone is promoting on CNN website on the comments :
http://money.cnn.com/2015/01/07/technology/bitcoin-taxes/and there is a thread on Bitcointalk about it here :
https://bitcointalk.org/index.php?topic=1023971.0 , the founder seem to be him :
https://bitcointalk.org/index.php?action=profile;u=257282 however he wasen't actif since May 2015
for what comes to the tax service you may wanna check this LibraTax (never tried it) but there is an article about it on Coindesk :
http://www.coindesk.com/libra-bitcoin-tax-service-irs-guidance/
