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[WaveChop]

I bought a track from the US worth 15 I received an amount of 6.30 on my account, but before that, there was always a sum of 7.50 I'm from Ukraine. Tax form W-8 filled. All pointed out. and earlier received for the same sold tracks for the US at 7.50.
Recently received 6.30, there was no previous tax - 1.20 US Royalty Withholding Tax
Where did he come from?

I will be happy for the detailed answer.

[Sealord]

… and earlier received for the same sold tracks for the US at $ 7.50.

then the buyer was not from the USA

sold to non-US buyer:
$15.00 - 20% = $12.00 (gross sale)
$12.00 * 0.375 = $4.50 (author fee)
$12.00 - $4.50 = $7.50 (net sale)

sold to US buyer:
$15.00 - 20% = $12.00 (gross sale)
$12.00 * 0.375 = $4.50 (author fee)
$12.00 * 0.10 = $1.20 (withholding tax)
$12.00 - $4.50 - $1.20 = $6.30 (net sale)