*Mt 22:
17 Tell us, then, what you think. Is it lawful to pay taxes to Caesar, or not?" 18 But Jesus, aware of their malice, said, “Why put me to the test, you hypocrites? 19 Show me the money for the tax.” And they brought him a coin. 20 And Jesus said to them, “Whose likeness and inscription is this?” 21 They said, “Caesar’s.” Then he said to them, “Render therefore to Caesar the things that are Caesar’s, and to God the things that are God’s.”
Thou shall not steal
Thou shall not bear false witness…
Thou shall not covet*
Greed is listed one of the deadly sins.
Consider carefully the above.
If you do not declare the money for the purpose of evading a lawful tax:
It is Greed - It is coveting - it is bearing false witness for the purpose of stealing…
Sounds pretty sinful to me.
Peace
James