I Am They suggests to play it in Bb 
Found this on essentialworship.com, and they have a lot of chords for songs as well. 
Hope this is useful :-) 
 
VERSE 1 
             C 
Waking up to a new sunrise 
                 Am 
Looking back from the other side 
          F                            Am            G 
I can see now with open eyes 
               C 
Darkest water and deepest pain 
                 Am 
I wouldn't trade it for anything 
                        F                      Am                    G 
Cause my brokenness brought me to You 
                       F                        Am                   G 
And these wounds are a story You'll use 
 
CHORUS 
               C       G/B                 Am 
So I'm thankful for the scars 
                            F                                        C         G/B   Am 
Cause' without them I wouldn't know Your heart 
                 F                               C               G/B        Am 
And I know they'll always tell of who You are 
            Eb                      Gm              F         Gm  Eb  Bb (1st time) 
So forever I am thankful for the scars 
 
VERSE 2 
                        C 
Now I'm standing in confidence 
                     Am 
With the strength of Your faithfulness 
 
                      F                  Am        G 
And I'm not who I was before 
 
               F                    Am             G 
No, I don't have to fear anymore 
 
BRIDGE 
Am                       F 
  I can see - I can see 
C                            G 
  How You delivered me 
Am                                    F 
  In Your hands - In Your feet 
C                          G 
  I found my victory 
 
END CHORUS 
          C         G/B                Am 
I'm thankful for Your scars 
                                                      C            G/B   Am 
Cause' without them I wouldn't know Your heart 
         F                                          C       G/B  Am 
And with my life I'll tell of who You are 
          F                            Am          G 
So forever I am thankful 
         Am             G/B            C 
I'm thankful for the scars 
                    Dm                                      Am          G/B  C 
Cause' without them I wouldn't know Your heart 
            Dm                               Am               G/B            C 
And I know they'll always tell of who You are 
         Dm                          F               G        Am    F    C 
So forever I am thankful for the scars 
                                      Am      F          C 
So forever I am thankful for the scars